Special Publication 800-101 

Sponsored by the Department 

of Homeland Security 

Guidelines on Cell Phone 

Forensics 

Recommendations of the National Institute 

of Standards and Technology 

Wayne Jansen 

Rick Ayers
NIST Special Publication 800-101 

C O M P U T E R S E C U R I T Y

Computer Security Division 

Information Technology Laboratory 

National Institute of Standards and Technology 

Gaithersburg, MD 20899-8930 

May 2007

U.S. Department of Commerce

Carlos Gutierrez, Secretary 

Technology Administration

Robert C. Cresanti, Under Secretary for Technology 

 National Institute of Standards and Technology 

William Jeffrey, Director 

Guidelines on Cell Phone 

Forensics 

Recommendations of the National 

Institute of Standards and Technology

Wayne Jansen 

Rick Ayers 
Reports on Computer Systems Technology 

The Information Technology Laboratory (ITL) at the National Institute of Standards and 

Technology (NIST) promotes the U.S. economy and public welfare by providing 

technical leadership for the Nation’s measurement and standards infrastructure. ITL 

develops tests, test methods, reference data, proof of concept implementations, and 

technical analysis to advance the development and productive use of information 

technology. ITL’s responsibilities include the development of technical, physical, 

administrative, and management standards and guidelines for the cost-effective 

security and privacy of sensitive unclassified information in Federal computer 

systems. This Special Publication 800-series reports on ITL’s research, guidance, and 

outreach efforts in computer security and its collaborative activities with industry, 

government, and academic organizations.

Certain commercial entities, equipment, or materials may be identified in this document in 

order to describe an experimental procedure or concept adequately. Such identification is 

not intended to imply recommendation or endorsement by the National Institute of 

Standards and Technology, nor is it intended to imply that the entities, materials, or 

equipment are necessarily the best available for the purpose. 

National Institute of Standards and Technology Special Publication 800-101 

Natl. Inst. Stand. Technol. Spec. Publ. 800-101, 104 pages (2007) 
Acknowledgements 

The authors, Wayne Jansen and Rick Ayers from NIST, wish to thank colleagues who 

reviewed drafts of this document. In particular, our appreciation goes to Tim Grance from 

NIST for his research, technical support, and written contributions to this document. Our 

appreciation also goes out to Ronald van der Knijff and his colleagues at the Netherlands 

Forensic Institute and Svein Willassen at the Norwegian University of Science and 

Technology for their assistance on technical issues that arose in our work. The authors would 

also like to thank Rick Mislan from Purdue University, Chris Sanft from the SEARCH Group, 

and all others who assisted with our review process. 

This work was sponsored by the Department of Homeland Security (DHS), whose support 

and guidance in this effort are greatly appreciated. 
Guidelines on Cell Phone Forensics 

Table of Contents 

TABLE OF CONTENTS............................................................................................................. V

LIST OF FIGURES ....................................................................................................................VII 

LIST OF TABLES.................................................................................................................... VIII 

EXECUTIVE SUMMARY........................................................................................................... 1 

1. INTRODUCTION.................................................................................................................. 3 

1.1 AUTHORITY ...................................................................................................................... 3 

1.2 PURPOSE AND SCOPE........................................................................................................ 3 

1.3 AUDIENCE AND ASSUMPTIONS......................................................................................... 4 

1.4 DOCUMENT STRUCTURE .................................................................................................. 4 

2. BACKGROUND.................................................................................................................... 6 

2.1 CELL NETWORK CHARACTERISTICS ................................................................................ 6 

2.2 MOBILE PHONE CHARACTERISTICS ................................................................................. 8 

2.3 IDENTITY MODULE CHARACTERISTICS.......................................................................... 11 

3. FORENSIC TOOLS............................................................................................................. 13 

3.1 (U)SIM TOOLS ............................................................................................................... 17 

3.2 HANDSET TOOLS ............................................................................................................ 18 

3.3 INTEGRATED TOOLKITS.................................................................................................. 20 

3.4 CAPABILITIES.................................................................................................................. 22 

4. PROCEDURES AND PRINCIPLES.................................................................................. 24 

4.1 ROLES AND RESPONSIBILITIES ....................................................................................... 24 

4.2 EVIDENTIAL PRINCIPLES ................................................................................................ 25 

4.3 PROCEDURAL MODELS................................................................................................... 26 

5. PRESERVATION................................................................................................................ 29 

5.1 SECURING AND EVALUATING THE SCENE...................................................................... 31 

5.2 DOCUMENTING THE SCENE ............................................................................................ 32 

5.3 COLLECTING THE EVIDENCE.......................................................................................... 33 

5.4 PACKAGING, TRANSPORTING, AND STORING EVIDENCE............................................... 36 

6. ACQUISITION..................................................................................................................... 38 

6.1 DEVICE IDENTIFICATION ................................................................................................ 39 

6.2 TOOL SELECTION AND EXPECTATIONS.......................................................................... 41 

6.3 MEMORY CONSIDERATIONS........................................................................................... 42 

6.4 UNOBSTRUCTED DEVICES.............................................................................................. 44 

6.5 OBSTRUCTED DEVICES................................................................................................... 48 

6.6 TANGENTIAL EQUIPMENT .............................................................................................. 53 

v
Guidelines on Cell Phone Forensics 

7. EXAMINATION AND ANALYSIS.................................................................................. 56 

7.1 POTENTIAL EVIDENCE.................................................................................................... 56 

7.2 APPLYING TOOLS ........................................................................................................... 59 

7.3 CALL AND SUBSCRIBER RECORDS ................................................................................. 61 

8. REPORTING........................................................................................................................ 65 

9. REFERENCES ..................................................................................................................... 68 

APPENDIX A. ACRONYMS .................................................................................................... 74 

APPENDIX B. GLOSSARY...................................................................................................... 77 

APPENDIX C. GENERIC ACQUISITION OVERVIEW....................................................... 82 

C.1 CONNECTION IDENTIFICATION....................................................................................... 82 

C.2 DEVICE IDENTIFICATION ................................................................................................ 82 

C.3 DATA SELECTION ........................................................................................................... 83 

C.4 ACQUISITION................................................................................................................... 84 

C.5 PHONEBOOK ENTRIES..................................................................................................... 85 

C.6 CALL LOG ENTRIES ........................................................................................................ 86 

C.7 MESSAGE ENTRIES ......................................................................................................... 87 

C.8 CALENDAR ENTRIES....................................................................................................... 88 

C.9 (U)SIM DATA................................................................................................................. 89 

C.10 PICTURE ENTRIES........................................................................................................ 90 

C.11 SEARCHING ................................................................................................................. 91 

C.12 REPORTING.................................................................................................................. 92 

APPENDIX D. STANDARDIZED CALL RECORDS ........................................................... 93 

APPENDIX E. ONLINE RESOURCES FOR MOBILE DEVICE FORENSICS ................. 95 

vi
Guidelines on Cell Phone Forensics 

List of Figures 

Figure 1: Cellular Network Organization........................... 8 

Figure 2: (U)SIM Format.................................................. 12 

Figure 3: Data Acquisition, Decoding, and Translation .. 13 

Figure 4: Storage Assignments ......................................... 43 

Figure 5: Alternative Storage Assignments...................... 43 

Figure 6: SIM File System ................................................ 44 

Figure 7: Connection Identification.................................. 82 

Figure 8: Device Acquisition ............................................ 83 

Figure 9: Data Selection.................................................... 84 

Figure 10: Acquisition....................................................... 85 

Figure 11: Phonebook Entries........................................... 86 

Figure 12: Call Log Entries............................................... 86 

Figure 13: SMS Text Messages........................................ 87 

Figure 14: Multimedia Message ....................................... 88 

Figure 15: Calendar Entries............................................... 89 

Figure 16: (U)SIM Data .................................................... 90 

Figure 17: Picture Entries.................................................. 91 

Figure 18: Search Facility ................................................. 91 

Figure 19: Report Facility ................................................. 92 

vii
Guidelines on Cell Phone Forensics 

List of Tables 

Table 1: Hardware Characterization................................... 9 

Table 2: Software Characterization .................................. 10 

Table 3: Example IMEI Acquisition................................. 14 

Table 4: Forensic Tools..................................................... 16 

Table 5: Memory Cards..................................................... 54 

Table 6: Cross Reference of Sources and Objectives ...... 59 

Table 7: Example Record Structure.................................. 93 

Table 8: Technical Resource Sites.................................... 95 

Table 9: Databases for Identification Queries.................. 95 

Table 10: Forensic Tools................................................... 95 

Table 11: Other Related Tools.......................................... 96 

 

viii
Guidelines on Cell Phone Forensics 

Executive Summary 

Mobile phone forensics is the science of recovering digital evidence from a mobile phone 

under forensically sound conditions using accepted methods. Mobile phones, especially those 

with advanced capabilities, are a relatively recent phenomenon, not usually covered in classical 

computer forensics. This guide attempts to bridge that gap by providing an in-depth look into 

mobile phones and explaining the technologies involved and their relationship to forensic 

procedures. It covers phones with features beyond simple voice communication and text 

messaging and their technical and operating characteristics. This guide also discusses 

procedures for the preservation, acquisition, examination, analysis, and reporting of digital 

information present on cell phones, as well as available forensic software tools that support 

those activities. 

The objective of the guide is twofold: to help organizations evolve appropriate policies and 

procedures for dealing with cell phones, and to prepare forensic specialists to contend with 

new circumstances involving cell phones, when they arise. The guide is not all-inclusive nor is 

it prescribing how law enforcement and incident response communities handle mobile devices 

during investigations or incidents. However, from the principles outlined and other 

information provided, organizations should nevertheless find the guide helpful in setting 

policies and procedures. This publication should not be construed as legal advice. 

Organizations should use this guide as a starting point for developing a forensic capability in 

conjunction with extensive guidance provided by legal advisors, officials, and management. 

The information in this guide is best applied in the context of current technology and practices. 

Every situation is unique, as are the experiences of the forensic specialists and the tools and 

facilities at their disposal. The judgment of the forensic specialists should be given deference 

in the implementation of the procedures suggested in this guide. Circumstances of individual 

cases; international, federal, state, local laws and rules; and organization-specific policies may 

also require actions other than those described in this guide. As always, close and continuing 

consultation with legal counsel is advised. 

Implementing the following recommendations should facilitate efficient and effective digital 

forensic activities involving cell phones and cellular devices. 

Organizations should ensure that their policies contain clear statements about forensic 

considerations involving cell phones. 

At a high level, policy should allow authorized personnel to perform investigations of 

organizationally issued cell phones for legitimate reasons, under the appropriate circumstances. 

The forensic policy should clearly define the roles and responsibilities of the workforce and of 

any external organizations performing or assisting with the organization’s forensic activities. 

The policy should also indicate internal teams and external organizations to be contacted under 

various circumstances. 

Organizations should create and maintain procedures and guidelines for performing 

forensic tasks on cell phones. 

Guidelines should focus on general methodologies for investigating incidents using forensic 

techniques. While developing comprehensive procedures tailored to every possible situation is 

ES-1
Guidelines on Cell Phone Forensics 

not generally feasible, organizations should consider developing step-by-step procedures for 

performing all routine activities in the preservation, acquisition, examination and analysis, and 

reporting of digital evidence found on cell phones and associated media. The guidelines and 

procedures should facilitate consistent, effective, accurate, and repeatable actions carried out in 

a forensically sound manner, suitable for legal prosecution or disciplinary actions. The 

guidelines and procedures should support the admissibility of evidence into legal proceedings, 

including seizing and handling evidence properly, maintaining the chain of custody, storing 

evidence appropriately, establishing and maintaining the integrity of forensic tools and 

equipment, and demonstrating the integrity of any electronic logs, records, and case files. The 

guidelines and procedures should be reviewed periodically, and also whenever significant 

changes in cell phone technology appear that affect them.

Organizations should ensure that their policies and procedures support the reasonable 

and appropriate use of forensic tools for cell phones. 

Policies and procedures should clearly explain what actions are to be taken by a forensic unit 

under various circumstances commonly encountered with cell phones. They should also 

describe the quality measures to apply in verifying the proper functioning of any forensic tools 

used in examining cell phones and associated media. Procedures for handling sensitive 

information that might be recorded by forensic tools should also be addressed. Legal counsel 

should carefully review all forensic policy and high-level procedures for compliance with 

international, federal, state, and local laws and regulations, as appropriate. 

Organizations should ensure that their forensic professionals are prepared to conduct 

activities in cell phone forensics. 

Forensic professionals, especially first responders to incidents, should understand their roles 

and responsibilities for cell phone forensics and receive training and education on related 

forensic tools, policies, guidelines, and procedures. Forensic professionals should also consult 

closely with legal counsel both in general preparation for forensics activities, such as 

determining which actions should and should not be taken under various circumstances. In 

addition, management should be responsible for supporting forensic capabilities, reviewing 

and approving forensic policy, and examining and endorsing unusual forensic actions that may 

be needed in a particular situation. 

ES-2
Guidelines on Cell Phone Forensics 

1. Introduction 

1.1 Authority 

The National Institute of Standards and Technology (NIST) developed this guide in 

furtherance of its statutory responsibilities under the Federal Information Security 

Management Act (FISMA) of 2002, Public Law 107-347. 

NIST is responsible for developing standards and guidelines, including minimum 

requirements, for providing adequate information security for all Federal agency operations 

and assets; but such standards and guidelines shall not apply to national security systems. This 

guideline is consistent with the requirements of the Office of Management and Budget (OMB) 

Circular A-130, Section 8b(3), “Securing Agency Information Systems,” as analyzed in A130, Appendix IV: Analysis of Key Sections. Supplemental information is provided in A-130, 

Appendix III. 

This guide has been prepared for use by Federal agencies. It may be used by nongovernmental organizations on a voluntary basis and is not subject to copyright, though 

attribution is desired. 

Nothing in this guide should be taken to contradict standards and guidelines made mandatory 

and binding on Federal agencies by the Secretary of Commerce under statutory authority, nor 

should these guidelines be interpreted as altering or superseding the existing authorities of the 

Secretary of Commerce, Director of the OMB, or any other Federal official. 

1.2 Purpose and Scope 

This guide provides basic information on the preservation, acquisition, examination, analysis, 

and reporting of digital evidence on cell phones, relevant to law enforcement, incident 

response, and other types of investigations. The guide focuses mainly on the characteristics of 

cell phones, including smart phones having advanced capabilities. It also covers provisions to 

be taken into consideration during the course of an incident investigation. 

The guide is intended to address common circumstances that may be encountered by 

organizational security staff and law enforcement investigators, involving digital electronic 

data residing on cell phones and associated electronic media. It is also intended to complement 

existing guidelines and delve more deeply into issues related to cell phones and their 

examination and analysis. 

Procedures and techniques presented in this document are a compilation of the authors’ 

opinions and references taken from existing forensic guidelines. The publication is not to be 

used as a step-by-step guide for executing a proper forensic investigation when dealing with 

mobile phones or construed as legal advice. Its purpose is to inform readers of the various 

technologies involved and potential ways to approach them from a forensic point of view. 

Readers are advised to apply the recommended practices only after consultation with 

management and legal officials for compliance with laws and regulations (i.e., local, state, 

federal, and international) that pertain to their situation. 

3
Guidelines on Cell Phone Forensics 

1.3 Audience and Assumptions 

The intended audience is varied and ranges from response team members handling a computer 

security incident to organizational security officials investigating an employee-related situation 

to forensic examiners involved in criminal investigations. The practices recommended in this 

guide are designed to highlight key technical principles associated with the handling and 

examination of electronic evidence, in general, and cell phones in particular. Readers are 

assumed to have a basic grounding in classical computer forensics involving individual 

computer systems (e.g., personal computers) and network servers. Because of the constantly 

changing nature of handheld devices and related forensic procedures and tools, readers are 

expected to take advantage of other resources, including those listed in this guide, for more 

current and detailed information. 

1.4 Document Structure 

The guide is divided into the following chapters and appendices: 

 Chapter 1 (this chapter) explains the authority, purpose and scope, audience and 

assumptions of the document, and outlines its structure. 

 Chapter 2 is an overview on cell phones, including an overview of common hardware 

and software capabilities. 

 Chapter 3 discusses present-day cell phone forensic tools and the types of devices 

with which they work. 

 Chapter 4 provides general information on procedures and principles that apply to cell 

phone forensics. 

 Chapter 5 discusses considerations for preserving digital evidence associated with cell 

phones. 

 Chapter 6 examines the process of acquisition of digital evidence from cell phones, as 

well as from common types of peripheral equipment. 

 Chapter 7 outlines common sources of evidence on cell phones and the features and 

capabilities of tools for examination. 

 Chapter 8 discusses the reporting of findings. 

 Chapter 9 contains a list of references used in this guide. 

 Appendix A contains a list of acronyms used in this guide. 

 Appendix B contains a glossary defining terms used in this guide. 

 Appendix C gives a summary of the steps involved in an acquisition. 

 Appendix D provides an example of the structure of call records maintained by cell 

phone carriers. 

4
Guidelines on Cell Phone Forensics 

 Appendix E provides links to online resources. 

5
Guidelines on Cell Phone Forensics 

2. Background 

The digital forensic community faces a constant challenge to stay abreast of the latest 

technologies that may be used to expose relevant clues in an investigation. Mobile phones are 

commonplace in today’s society, used by many individuals for both personal and professional 

purposes. Mobile phone forensics is the science of recovering digital evidence from a mobile 

phone under forensically sound conditions using accepted methods. Cell phones vary in 

design and are continually undergoing change as existing technologies improve and new 

technologies are introduced. When a cell phone is encountered during an investigation, many 

questions arise: What should be done about maintaining power? How should the phone be 

handled? How should valuable or potentially relevant data contained on the device be 

examined? The key to answering these questions is an understanding of the hardware and 

software characteristics of cell phones. 

This chapter gives an overview of the hardware and software capabilities of cell phones and 

their associated cellular networks. The overview provides a summary of general 

characteristics and, where useful, focuses on key features. Developing an understanding of the 

components and organization of cell phones (e.g., memory organization and use) is a 

prerequisite to understanding the criticalities involved when dealing with them forensically. 

For example, cell phone memory that contains user data may be volatile (i.e., RAM) and 

require continuous power to maintain content, unlike a personal computer’s hard disk. 

Similarly, features of cellular networks are an important aspect of cell phone forensics, since 

logs of usage and other data are maintained therein. Handheld device technologies and cellular 

networks are rapidly changing, with new technologies, products, and features being introduced 

regularly. Because of the fast pace with which cellular device technologies are evolving, this 

discussion captures a snapshot of the cell phone area at the present time. 

2.1 Cell Network Characteristics 

Within the U.S., different types of digital cellular networks abound that follow distinct 

incompatible sets of standards. The two most dominant types of digital cellular networks are 

known as Code Division Multiple Access (CDMA) and Global System for Mobile 

Communications (GSM) networks. Other common cellular networks include Time Division 

Multiple Access (TDMA) and Integrated Digital Enhanced Network (iDEN). IDEN networks 

use a proprietary protocol designed by Motorola, while the others follow standardized open 

protocols. A digital version of the original analog standard for cellular telephone phone 

service, called Digital Advanced Mobile Phone Service (D-AMPS), also exist. 

CDMA refers to a technology designed by Qualcomm in the U.S., which employs spread 

spectrum communications for the radio link. Rather than sharing a channel as many other 

network air interfaces do, CDMA spreads the digitized data over the entire bandwidth 

available, distinguishing multiple calls through a unique sequence code assigned. Successive 

versions of the IS-95 standard define CDMA conventions in the U.S., which is the reason why 

the term CDMA is often used to refer to IS-95 compliant cellular networks. IS-95 CDMA 

systems are sometimes referred to as cdmaOne. The next evolutionary step for CDMA to 3G 

6
Guidelines on Cell Phone Forensics 

 

services is cdma2000, TIA/EIA/IS-2000 Series1

, Release A, based on the ITU IMT-2000 

standard. Both Verizon and Sprint operate nationwide CDMA networks in the U.S. 

GSM is a cellular system used worldwide that was designed in Europe, primarily by Ericsson 

and Nokia. Cingular and T-Mobile operate nationwide networks in the U.S. GSM uses a 

TDMA air interface. TDMA refers to a digital link technology whereby multiple phones share 

a single carrier, radio frequency channel by taking turns – using the channel exclusively for an 

allocated time slice, then releasing it and waiting briefly while other phones use it. A packet 

switching enhancement to GSM wireless networks called General Packet Radio Service 

(GPRS) was standardized to improve the transmission of data. The next generation of GSM, 

commonly referred to as the third generation or 3G, is known as Universal Mobile 

Telecommunications System (UMTS) and involves enhancing GSM networks with a 

Wideband CDMA (W-CDMA) air interface. 

TDMA is also used to refer specifically to the standard covered by IS-136, which defines a 

specific type of cellular network. Using the term TDMA to refer to a general technique or a 

specific type of cellular network can be a source of confusion. For example, although GSM 

uses a TDMA air interface (i.e., the general technique), as does iDEN, neither of those systems 

is compatible with so-called TDMA cellular networks that follow IS-136. 

Mobile phones work with certain subsets of the network types mentioned, typically those 

associated with the service provider providing the phone and from whom a service agreement 

was arranged. For example, a service provider or network operator for a GSM network that 

has some older TDMA network segments in operation might supply a phone that has GSM 

voice and data capabilities, and TDMA capabilities. Such a phone would not be compatible 

with CDMA networks. Mobile phones can also be acquired without service from a 

manufacturer, vendor, or other source, and have their service set up separately with a service 

provider or network operator, provided that the phone is compatible with the network. When 

in operation, mobile phones may contact compatible networks operated for or by another 

service provider, and gain service. To administer the cellular network system, provide 

subscribed services, and accurately bill or debit subscriber accounts, data about the service 

contract and associated service activities are captured and maintained by the network system. 

As the name implies, cellular networks provide coverage based on dividing up a large 

geographical service area into smaller areas of coverage called cells. Cells play an important 

role in reuse of radio frequencies in the limited radio spectrum available to allow more calls to 

occur than otherwise would be possible. As a mobile phone moves from one cell to another, 

however, a cellular arrangement requires active connections to be monitored and effectively 

passed along between cells to maintain the connection 

Despite their differences in technology, cellular networks are organized similarly to one 

another, in a manner illustrated in Figure 1. The main components are the radio transceiver 

equipment that communicates with mobile phones, the controller that manages the transceiver 

equipment and performs channel assignment, and the switching system for the cellular 

network. The technical names for these components are respectively the Base Transceiver 

Station (BTS), the Base Station Controller (BSC), and the Mobile Switching Center (MSC). 

The BSC and the BTS units it controls are sometimes collectively referred to as a Base Station 

1

 Available at the following site: http://www.tiaonline.org/standards/technology/cdma2000/cdma2000table.cfm

7
Guidelines on Cell Phone Forensics 

Subsystem. The transceivers at the BTS can be configured in a variety of ways. A typical 

configuration involves three distinct sectors of 120 degree coverage: 0 degrees North to 120 

degrees Southeast, 120 degrees Southeast to 240 degrees Southwest, and 240 degrees 

Southwest to 360 degrees North. A cell identifier uniquely identifies the BTS and sector 

involved in servicing a call. 

Figure 1: Cellular Network Organization 

The MSC controls a set of BSCs and manages overall communications throughout the cellular 

network, including interfacing to the public switch telephone network. To perform its tasks, 

the MSC uses several databases. A key database is the central repository system for subscriber 

data and service information, called the Home Location Register (HLR). Another database 

used in conjunction with the HLR for mobile phones roaming outside of their service area is 

the Visitor Location Register. Account information, such as data about the subscriber (e.g., a 

billing address), the subscribed services, and the location update last registered with the 

network are maintained at the HLR and used by the MSC to route calls and messages and to 

generate usage records called call detail records. The subscriber account data and call detail 

records are often a valuable source of evidence in an investigation. 

2.2 Mobile Phone Characteristics 

Mobile phones are highly mobile communications devices that perform an array of functions 

ranging from that of a simple digital organizer to that of a low-end personal computer. 

Designed for mobility, they are compact in size, battery powered, and lightweight. Most cell 

phones have a basic set of comparable features and capabilities. They house a microprocessor, 

read only memory (ROM), random access memory (RAM), a radio module, a digital signal 

processor, a microphone and speaker, a variety of hardware keys and interfaces, and a liquid 

crystal display (LCD). The operating system (OS) of the device is held in ROM, which with 

the proper tools typically can be erased and reprogrammed electronically. RAM, which for 

8
Guidelines on Cell Phone Forensics 

certain models may be used to store user data, is kept active by batteries, whose failure or 

exhaustion causes that information to be lost. 

The latest cell phones come equipped with system-level microprocessors that reduce the 

number of supporting chips required and include considerable memory capacity. Built-in Mini 

Secure Digital (MiniSD)2

, MultiMedia Card Mobile (MMCmobile)3, or other types of card 

slots support removable memory cards or specialized peripherals, such as an SDIO WiFi card. 

Wireless communications such as infrared (i.e., IrDA) or Bluetooth may also be built into the 

device. 

Different devices have different technical and physical characteristics (e.g., size, weight, 

processor speed, memory capacity). Devices may also use different types of expansion 

capabilities to provide additional functionality. Furthermore, cell phone capabilities 

sometimes include those of other devices such as PDAs, global positioning systems, and 

cameras. Overall, they can be classified as basic phones that are primarily simple voice and 

messaging communication devices; advanced phones that offer additional capabilities and 

services for multimedia; and smart phones or high-end phones that merge the capabilities of an 

advanced phone with those of a PDA. Table 1 highlights the general hardware characteristics 

of basic, advanced, and smart phone models, which underscore this diversity. 

Table 1: Hardware Characterization 

Basic Advanced Smart 

Processor Limited Speed Improved Speed Superior Speed 

Memory Limited Capacity Improved Capacity Superior Capacity, Built-in 

Hard Drive Possibility 

Display Grayscale Color Large size, 16-bit Color 

(65,536 colors) or Higher 

Card Slots None MiniSD or MMCmobile MiniSDIO or MMCmobile 

Camera None Still Still, Video 

Text Input Numeric Keypad Numeric Keypad, Soft 

Keyboard 

Touch Screen, 

Handwriting Recognition, 

Built-in QWERTY-style 

Keyboard 

Cell 

Interface 

Voice and Limited Data Voice and High Speed 

Data 

Voice and Very High 

Speed Data 

Wireless IrDA IrDA, Bluetooth IrDA, Bluetooth, WiFi 

Battery Fixed, Rechargeable 

Lithium Ion Polymer 

Removable, 

Rechargeable Lithium Ion 

Polymer 

Removable, 

Rechargeable Lithium Ion 

Note that the characteristics used in this classification scheme are illustrative. The features of 

actual devices do vary and can span more than one category identified. Over time, advanced 

 

2

 The Secure Digital home page can be found at: http://www.Sdcard.org

3

 The MultiMediaCard home page can be found at: http://www.mmca.org

9
Guidelines on Cell Phone Forensics 

features also tend to appear in more basic phones as new ones are added to the high end. 

Though the lines among this classification scheme are somewhat fuzzy and dynamic, it 

nevertheless serves as a general guide. 

Despite the type of cell phone, nearly all devices support voice and text messaging, a set of 

basic Personal Information Management (PIM) applications that includes phonebook and date 

book facilities, and a means to synchronize PIM data with a desktop computer. More 

advanced devices also provide the ability to perform multimedia messaging, connect to the 

Internet and surf the Web, exchange electronic mail, or chat using instant messaging. They 

may also provide enhanced PIM applications that work with specialized built-in hardware, 

such as a camera. 

Finally, very high-end devices called smart phones add PDA-like capability for reviewing 

electronic documents (e.g., reports, briefing slides, and spreadsheets) and running a wide 

variety of general and special-purpose applications. Smart phones are typically larger than 

other phones, support a bigger-size display (e.g., 1⁄4 VGA and higher), and may have an 

integrated QWERTY keyboard or touch sensitive screen. They also offer more extended 

expansion capabilities through peripheral card slots, other built-in wireless communications 

such as Bluetooth and WiFi, and synchronization protocols to exchange other kinds of data 

beyond basic PIM data (e.g., graphics, audio, and archive file formats). Table 2 lists the 

differences in software capabilities found on these device classes. 

Table 2: Software Characterization 

Basic Advanced Smart 

OS Proprietary Proprietary Linux, Windows Mobile, RIM 

OS, Palm OS, Symbian 

PIM Simple Phonebook Phonebook and Calendar Reminder List, Enhanced 

Phonebook and Calendar 

Applications None MP3 Player MP3 Player, Office 

Document Viewing 

Messaging Text Messaging 

Text with Simple 

Embedded Images and 

Sounds (Enhanced Text) 

Text, Enhanced Text, 

Full Multimedia Messaging 

Chat None SMS Chat Instant Messaging 

Email None Via Network Operator’s 

Service Gateway Via POP or IMAP Server 

Web None Via WAP Gateway Direct HTTP 

Wireless IrDA IrDA, Bluetooth IrDA, Bluetooth, WiFi 

The basic and advanced cell phones typically use a company proprietary operating system. A 

number of companies specializing in embedded software also offer real-time operating system 

solutions for manufacturers of portable devices, including cell phones. Nearly all cell phones 

claiming to be smart phones use one of the following operating systems: Palm OS, Windows 

Mobile (phone edition), RIM OS, Symbian OS, or Linux. Unlike the more limited, real-time 

kernels in basic and advanced phones, these operating systems are multi-tasking and fullfeatured, designed specifically to match the capabilities of high-end mobile devices. Besides a 

wide array of applications, they often come complete with a Java Virtual Machine and native 

10
Guidelines on Cell Phone Forensics 

 

application support using a Software Development Kit (SDK) for C++ or another language. 

Characteristics of a wide range of past, current, and future cell phones can be found on 

manufacturer and vendor Web sites, as well as product review sites.4

2.3 Identity Module Characteristics 

Subscriber Identity Modules are synonymous with mobile phones and devices that interoperate 

with GSM cellular networks. Under the GSM framework, a cellular phone is referred to as a 

Mobile Station and is partitioned into two distinct components: the Subscriber Identity Module 

(SIM) and the Mobile Equipment (ME). As the name implies, a SIM is a removable 

component that contains essential information about the subscriber. The ME, the remaining 

radio handset portion, cannot function fully without one. The SIM’s main function entails 

authenticating the user of the cell phone to the network to gain access to subscribed services. 

The SIM also provides storage for personal information, such as phone book entries and text 

messages, as well as service-related information. 

The SIM-ME partitioning of a cell phone stipulated in the GSM standards has brought about a 

form of portability. Moving a SIM between compatible cell phones automatically transfers 

with it the subscriber’s identity and the associated information and capabilities. In contrast, 

present-day CDMA phones do not employ a SIM. Analogous SIM functionality is instead 

directly incorporated within the device. While SIMs are most widely used in GSM systems, 

comparable modules are also used in iDEN phones and UMTS user equipment (i.e., a USIM). 

Because of the flexibility a SIM offers GSM phone users to port their identity, personal 

information, and service between devices, eventually all cellular phones are expected to 

include (U)SIM-like capability. For example, requirements for a Removable User Identity 

Module (R-UIM), as an extension of SIM capabilities, have been specified for cellular 

environments conforming to TIA/EIA/IS-95-A and -B specifications, which include Wideband 

Spread Spectrum based CDMA [3GP02]. 

At its core, a (U)SIM is a special type of smart card that typically contains a processor and 

between 16 to 128 KB of persistent electronically erasable, programmable read only memory 

(EEPROM). It also includes RAM for program execution and ROM for the operating system, 

user authentication and data encryption algorithms, and other applications. The (U)SIM’s 

hierarchically organized file system resides in persistent memory and stores such things as 

names and phone number entries, text messages, and network service settings. Depending on 

the phone used, some information on the (U)SIM may coexist in the memory of the phone. 

Information may also reside entirely in the memory of the phone instead of available memory 

reserved for it in the file system of the (U)SIM [Wil05, Jan06]. 

The (U)SIM operating system controls access to elements of the file system [3GP05a]. 

Actions such are reading or updating can be permitted or denied unconditionally, or allowed 

conditionally with certain access rights. Rights are assigned to a subscriber through 4-8 digit 

Personal Identification Number (PIN) codes. PINs protect core (U)SIM subscriber-related 

data and certain optional data. PIN codes can be modified by the subscriber, and their function 

disabled or enabled. A preset number of attempts, usually three, are allowed for providing the 

correct PIN code to the (U)SIM before further attempts are blocked completely, rendering 

communications inoperative. Only by providing a correct PIN Unblocking Key (PUK) can the 

4

 For example, specifications and product reviews for many current cell phones can be found at http://www.cnet.com.

11
Guidelines on Cell Phone Forensics 

value of a PIN and its attempt counter be reset on the (U)SIM. If the number of attempts to 

enter the correct PUK value exceeds a set limit, normally ten attempts, the card becomes 

blocked permanently. The PUK for a PIN can be obtained from the service provider or 

network operator by providing the identifier of the SIM (i.e., its Integrated Circuit Chip 

Identifier or ICCID). The ICCID is normally imprinted on the (U)SIM, but can also be read 

from an element of the file system. 

(U)SIMs have a width of 25 mm, a height of 15 mm, and a thickness of .76 mm, which is 

roughly the footprint of a postage stamp. Though similar in dimension to a MiniSD or an 

MMCmobile removable memory card supported by some cell phones, (U)SIMs follow a 

different set of specifications with vastly different characteristics. For example, their pin 

connectors are not aligned along a bottom edge as with removable media cards, but instead 

form a circular contact pad integral to the smart card chip, which is embedded in a plastic 

frame, as shown in Figure 2. (U)SIMs also employ a broad range of tamper resistance 

techniques to protect the information they contain. 

Figure 2: (U)SIM Format 

The slot for the (U)SIM card is normally not accessible from the exterior of the phone to 

facilitate frequent insertion and removal as with a memory card. Instead, it typically is found 

in the battery compartment under the battery. When a (U)SIM is inserted into a phone handset 

and pin contact is made, a serial interface is used for communicating between them. A 

(U)SIM can be removed from a phone and read using a specialized (U)SIM reader and 

software through the same interface. Standard-size smart card adapters are also available for 

(U)SIMs, which allows them to be inserted into and read with a conventional smart card 

reader. 

Authenticating a device to a network securely is a vital function performed via the SIM. 

Cryptographic key information and algorithms within the tamper resistant module provide the 

means for the device to participate in a challenge-response dialogue with the network and 

respond correctly, without exposing key material and other information that could be used to 

clone the SIM and gain access to a subscriber’s services. Cryptographic key information in the 

SIM also supports stream cipher encryption to protect against eavesdropping on the air 

interface [Ved93, Wil03]. 

12
Guidelines on Cell Phone Forensics 

3. Forensic Tools 

The situation with forensic software tools for cell phones is considerably different from 

personal computers. While personal computers are designed as general-purpose systems, cell 

phones are designed more as special-purpose appliances that perform a set of predefined tasks. 

Cellular phone manufacturers also tend to rely on assorted proprietary operating systems rather 

than the more standardized approach found in personal computers. Because of this, the variety 

of toolkits for mobile devices is diverse and the range of devices over which they operate is 

typically narrowed to distinct platforms for a manufacturer’s product line, an operating system 

family, or a type of hardware architecture. Short product release cycles are the norm for 

cellular phones, requiring tool manufacturers to update their tools continually to keep coverage 

current. The task is formidable and tool manufacturers’ support for newer models often lags 

significantly. Some have argued that the current state is likely to continue, keeping the cost of 

examination significantly higher than if a few standard operating systems prevailed [Moo06]. 

Forensic tools acquire data from a device in one of two ways: physical acquisition or logical 

acquisition. Physical acquisition implies a bit-by-bit copy of an entire physical store (e.g., a 

memory chip), while logical acquisition implies a bit-by-bit copy of logical storage objects 

(e.g., directories and files) that reside on a logical store (e.g., a file system partition). The 

difference lies in the distinction between memory as seen by a process through the operating 

system facilities (i.e., a logical view), versus memory as seen in raw form by the processor and 

other related hardware components (i.e., a physical view). 

Physical acquisition has advantages over logical acquisition, since it allows deleted files and 

any data remnants present (e.g., in unallocated memory or file system space) to be examined, 

which otherwise would go unaccounted. Extracted device images need to be parsed, decoded, 

and translated to uncover the data present. The work is tedious and time consuming to perform 

manually. Physical device images can be imported into a tool to automate examination and 

reporting, however, only a few tools tailored for obtaining cell phone images are currently 

available. A logical acquisition, though more limited than a physical acquisition, has the 

advantage that the system data structures are normally easier for a tool to extract and provide a 

more natural organization to understand and use during examination. If possible, doing both 

types of acquisition is preferable – a physical acquisition before a logical acquisition. 

Figure 3: Data Acquisition, Decoding, and Translation 

13
Guidelines on Cell Phone Forensics 

Most forensic software tools for cell phones and (U)SIMs acquire data logically, using 

common device protocols for synchronization, communications, and debugging, as shown in 

Figure 3 [Gra02, Mcc05]. Some tools may also be capable of acquiring data physically for 

certain classes of phones. AT commands, Sync ML, and the other protocols listed are 

commonly used in the logical acquisition of cell phones. Because handsets can support 

multiple protocols, a tool may employ several of them in succession to acquire the broadest 

range of available data. Even if a tool uses multiple protocols for a particular handset, all of 

the data available may not be able to be retrieved. 

Different tools can use a different protocol to acquire the same data. Table 3 illustrates the 

protocol exchanges used by several tools to acquire the IMEI (i.e., ASCII value of 

356661005704092) from a Nokia 6101 cell phone. The first tool listed uses a standardized AT 

Command exchange [Nok05], while the other two tools use the FBUS protocol [Pea05]. 

While many of the protocols are standardized and publicly available, some such as MBUS and 

FBUS are proprietary. Even standardized protocols often include manufacturer extensions or 

variants. (U)SIMs follow stricter standards than handsets and the application protocol data 

unit (APDU) interface protocol listed in Figure 3 is normally used exclusively with them. 

Table 3: Example IMEI Acquisition 

Request/Response (Hex) Request/Response (ASCII) 

41 54 2B 43 47 53 4E 0D A T + C G S N . GSM .XRY 0D 0A 33 35 36 36 36 31 30 30 35 37 30 34 30 

39 32 0D 0A 0D 0A 4F 4B 0D 0A

. . 3 5 6 6 6 1 0 0 5 7 0 4 0 9 2 . . .

. O K . .

1E 00 0C 7F 00 02 D2 01 C0 7C 1E 00 10 1B 

00 07 00 01 00 00 41 01 41 00 0E 1C 

. . . . . Ò . À | . . . . . . . . . . A . A  . 

. . PhoneBase 

1E 10 00 7F 00 02 1B 01 05 6C 1E 10 00 1B 

00 1C 01 39 00 01 00 01 41 14 00 10 33 35 36 

36 36 31 30 30 35 37 30 34 30 39 32 00 01 42 

5B 50

. . . . . . . . l . . . . . . . 9 . . . . A . . . 

3 5 6 6 6 1 0 0 5 7 0 4 0 9 2 . . B [ 

P

55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 

55 55 55 55 55 55 55 55 55 55 55 55 55 55 55 

 ... (6 more rows) 

1E 00 10 1B 00 07 00 04 00 00 41 01 60 00 2F 

19 

U U U U U U U U U U U U U U U 

U U U U U U U U U U U U U U U 

 ... 

. . . . . . . . . . A . ` . / .

Secure 

View 

1E 10 00 7F 00 02 1B 00 05 6D 1E 10 00 1B 

00 1C 04 39 00 01 00 01 41 14 00 10 33 35 36 

36 36 31 30 30 35 37 30 34 30 39 32 00 01 45 

5E 57

. . . . . . . . m . . . . . . . 9 . . . . A . . 

. 3 5 6 6 6 1 0 0 5 7 0 4 0 9 2 . . E 

^ W

The raw data logically acquired from a phone or (U)SIM is often encoded unconventionally, 

such as with text represented in the 7-bit GSM alphabet, and difficult to interpret. Other 

encodings that can be encountered include Binary Coded Decimal (BCD) and Unicode. To 

facilitate interpretation, most tools decode the data for the operator, as illustrated in Figure 3. 

Some tools go a step further and, where appropriate, translate the decoded data (e.g., numeric 

codes representing a country and a network operator) into more meaningful forms (e.g., 

country and network operator names) using a database (DB). 

The types of software tools available for cell phone examination include commercial forensic 

tools, device management tools, open source tools, self-developed tools, diagnostic tools, and 

hacker tools. Forensic tools are typically designed to acquire data from the internal memory of 

14
Guidelines on Cell Phone Forensics 

a handset and any removable identity modules such as SIMs found in GSM and other types of 

phones. Both forensic and non-forensic software tools often use the same protocols to 

communicate with the device. However, non-forensic tools allow a two-way flow of 

information to enhance or customize one’s cellular device (e.g., to add customized phone 

rings, wallpaper, themes, etc.), while forensic tools are designed specifically to acquire data 

from the device without altering device content and to calculate integrity hashes over the 

acquired data. Most practitioners use a collection of both forensic and non-forensic tools along 

with other accessories to form their “toolbox.”5

 Tools not designed specifically for forensic 

purposes are questionable, however [New07]. Before considering their use, they should be 

thoroughly evaluated and the implications of any associated forensic issues should be fully 

understood. In some situations, non-forensic tools might be the only means to retrieve data 

that could be relevant as evidence and may be appropriate to use when the proper precautions 

are taken. 

Port Monitoring: On occasion one might be faced with having to use a non-forensic tool, such 

as a phone manager, to recover data. Besides using test phones in thoroughly evaluating and 

understanding the tool, some additional steps can be considered. One of the easiest things to do, 

not only during the tool evaluation, but also during an actual acquisition once the evaluation has 

been completed, is to capture the protocol exchanges that occur over the serial connection 

between the phone and forensic workstation. Port monitors with such logging capabilities for 

cabled devices include Portmon6 and Serial Monitor.7 Infrared and Bluetooth monitoring is also 

possible using a separate workstation to eavesdrop on the wireless communications. 

During evaluation, the protocol exchanges can be analyzed for specific actions taken at the user 

interface and benign actions identified. During an actual acquisition, capturing the protocol 

exchanges serves as a record of the events that occurred, which can be kept for reference to 

refute any concerns that may be raised at a later time. 

Port monitoring can also be carried out with a forensic tool to gain insight on its operation or 

simply to capture a complete log of an acquisition. For example, the entries shown in Table 3 

were captured this way. Monitoring of (U)SIM tool exchanges can be done similarly. Built-in 

logging of protocol exchanges is a useful feature that some forensic tools provide, and precludes 

the need for a separate tool. 

While most forensic tools support a full range of acquisition, examination, and reporting 

functions, some tools focus only on a subset. Different tools may also support different 

interfaces (e.g., IrDA, Bluetooth, or serial cable) to acquire device contents. Acquisition 

through a cable interface generally yields superior results than other interfaces. However, 

under certain conditions, a wireless interface such as infrared or Bluetooth can serve as a 

reasonable alternative (e.g., when the correct cable is not readily available and the forensic 

issues of using another interface are understood). Regardless of the interface used, vigilance of 

the potential forensic issues associated is paramount. For example, Bluetooth typically 

involves an exchange of information with the forensic workstation to setup a connection, 

 

5

 For an example of recommended tools to include in an investigator’s toolkit, see 

http://www.search.org/files/pdf/CellphoneInvestToolkit-0806.pdf. 

6

 For more information, see http://www.sysinternals.com/Utilities/Portmon.html. 

7

 For more information, see http://www.hhdsoftware.com/sermon.html. 

15
Guidelines on Cell Phone Forensics 

which is then retained on the device. Enabling the connection and pairing the device to the 

workstation also requires key entries on the handset. 

Most forensic software tools address a wide range of applicable devices, handle the most 

common investigative situations, and require a modest level of skill to operate. Table 4 gives 

an overview of available tools used in cell phone investigations, and identifies the facilities 

they provide: acquisition, examination, or reporting. Additional tools do exist, but only those 

familiar to the authors are discussed. The tools are grouped into tools that target SIMs 

exclusively, tools that target handsets exclusively, and toolkits that target both handsets and 

SIMs. The range of devices a tool addresses is often narrowed to those from certain 

manufacturers, with specific operating systems, or with distinct hardware architectures. To 

cover the broadest range of mobile phones and (U)SIMs, a set of several tools is required. 

More detailed information about the performance forensic tools can be found in two 

companion reports [Aye05, Aye07]. The remaining sections of this chapter give a synopsis for 

each category of tool and an overview of their capabilities. Note that the capabilities of the 

tools listed are constantly improving and may differ slightly from the description given. 

Table 4: Forensic Tools 

Function Target Devices 

Forensic Card Reader Acquisition, Reporting  SIMs 

ForensicSIM 

Acquisition, 

Examination, 

Reporting 

 SIMs and USIMs 

SIMCon8

Acquisition, 

Examination, 

Reporting 

 SIMs and USIMs 

SIMIS 

Acquisition, 

Examination, 

Reporting 

 SIMs and USIMs 

USIMdetective 

Acquisition, 

Examination, 

Reporting 

 SIMs and USIMs 

BitPIM Acquisition, 

Examination 

 Certain CDMA phones using Qualcomm 

chipsets 

Oxygen PM 

(forensic version) 

Acquisition, 

Examination, 

Reporting 

 Nokia phones 

Oxygen PM for 

Symbian (forensic 

version) 

Acquisition, 

Examination, 

Reporting 

 Symbian phones 

PDA Seizure9

Acquisition, 

Examination, 

Reporting 

 Palm OS, Windows Mobile/Pocket PC, 

and Blackberry devices 

Pilot-Link Acquisition  Palm OS devices 

 

8

 During the preparation of this guide, SIMCon was acquired by Paraben and incorporated into its product line. 

9

 During the preparation of this guide, PDA Seizure was incorporated into Device Seizure, a forensic application for 

mobile devices. For more information, see www.paraben-forensics.com. 

16
Guidelines on Cell Phone Forensics 

Function Target Devices 

Cell Seizure10

Acquisition, 

Examination, 

Reporting 

 TDMA, CDMA, and GSM phones 

 SIMs and USIMs 

CellDEK 

Acquisition, 

Examination, 

Reporting 

 GSM and CDMA phones 

 SIMs and USIMs 

GSM .XRY 

Acquisition, 

Examination, 

Reporting 

 GSM and CDMA phones 

 SIMs and USIMs 

MobilEdit! 

Acquisition, 

Examination, 

Reporting 

 GSM phones 

 SIMs 

PhoneBase 

Acquisition, 

Examination, 

Reporting 

 GSM phones 

 SIMs and USIMs 

Secure View 

Acquisition 

Examination 

Reporting 

 TDMA, CDMA, and GSM phones 

 SIMs 

TULP 2G Acquisition, Reporting  GSM phones 

 SIMs 

3.1 (U)SIM Tools 

A few forensics tools deal exclusively with (U)SIMs. These tools perform a direct read of a 

module’s contents via a (U)SIM reader, as opposed to an indirect read via the phone handset. 

The richness and scope of data acquired varies with the capabilities and features of the tool. 

The majority of (U)SIM exclusive tools acquire the following data: International Mobile 

Subscriber Identity (IMSI), Integrated Circuit Card ID (ICCID), Abbreviated Dialling 

Numbers (ADN), Last Numbers Dialled (LND), SMS messages, and Location Information 

(LOCI) [Aye05, Aye07]. 

More capable tools provide additional information such as deleted SMS messages, properly 

rendered foreign language SMS messages, and EMS messages with simple graphics and 

sounds embedded [Jan06]. They also attempt to translate certain data such as country and 

network operator codes into meaningful names, and provide other facilities such as PIN 

administration. Below is a brief overview of some tools that are designed to acquire data 

specifically from SIMs. 

 Forensic Card Reader (FCR) is a forensic tool from Becker & Partner that provides 

the means to extract data from SIMs. FCR does not generate a case file, but outputs 

the acquired data in an XML-format that can be viewed with the appropriate editor. 

FCR consists of the software and a proprietary USB smart card reader necessary for 

acquisition. Neither integrity hash protection nor customizable report facilities are 

provided. 

 

10 During the preparation of this guide, Cell Seizure was incorporated into Device Seizure, a forensic application for 

mobile devices. For more information, see www.paraben-forensics.com. 

17
Guidelines on Cell Phone Forensics 

 The Forensic SIM Toolkit (FST) is a forensic tool from Radio Tactic that provides the 

means to extract and duplicate data from SIMs/USIMs. The case file is stored in a 

proprietary FST format and can be output in either an HTML or RTF/Word fileformat. A USB dongle is needed to operate the software on a desktop computer. The 

FST acquisition terminal, a standalone unit, duplicates the contents of the target 

(U)SIM to a set of FST data storage cards (i.e., the Master Data Storage Card, 

Defense Data Storage Card, and Prosecution Data Storage Card). Data analysis can 

be carried out using the appropriate FST data storage card with the ForensicSIM card 

reader (i.e., PC/SC-compatible card reader) attached to a PC running the ForensicSIM 

analysis application. An MD5 checksum provides integrity protection for the 

generated case data. FST allows the import of archived case files and basic searches 

of the acquired data file. 

 SIMCon is a forensic tool from InsideOut Forensics that provides the means to extract 

data from SIMs and USIMs. The case file has a proprietary format but can be 

exported to a standard ASCII text format. Additional hardware (e.g., USB dongle, 

proprietary card readers) are not necessary for acquisition. SIMCon acquires data 

from a (U)SIM via a PC/SC-compatible card reader and uses a SHA1 hash to protect 

the integrity of the generated case data. SIMCon provides the ability to import 

archived case files and export specific data out into a final report. 

 SIMIS is a forensic tool from Crownhill USA that provides means to extract data 

from SIMs and USIMs. The case file is generated in an HTML file-format. An 

additional “SIM dump” feature provides a more detailed case file in a standard ASCII 

text format. A USB dongle is needed to operate the software on a desktop computer. 

SIMIS acquires information from a (U)SIM via a PC/SC-compatible card reader and 

generates MD5 and SHA2 hashes of the acquired data. SIMIS provides the ability to 

create report notes, import archived case files, search acquired data, and administer 

PINs. The search function can range over any archived SIMs present in the program 

folder. 

 Quantaq Solutions’ USIMdetective SIM acquisition tool provides examiners with the 

ability to acquire, examine, and produce reports from any SIM or USIM card using a 

PC/SC compatible reader. Acquired elements can be displayed in a textual or 

hexadecimal format. USIMdetective uses an internal hashing facility to ensure the 

integrity of case. Image Integrity Check (.iic) files are created with each acquisition to 

protect against data tampering. SHA1 and MD5 hashes ensure that the original 

acquired file is consistent with the reopened case file. USIMdetective provides 

multiple report output types ranging from a “Standard Report” to a more detailed 

“File Content Report.” 

3.2 Handset Tools 

A few forensic tools deal with handsets exclusively, designed strictly for the acquisition of 

their internal memory. These tools sometimes stem from tools aimed at pure PDA devices and 

thus are useful with smart phones that incorporate operating systems with a PDA heritage, 

such as Palm OS and Windows Mobile devices. Others have arisen from phone management 

software modified to disable writing to the device. They generally exclude the capability to 

acquire data from SIMs using a direct read. Below is a brief overview of some tools designed 

for memory acquisition from mobile devices with cellular capabilities. 

18
Guidelines on Cell Phone Forensics 

 PDA Seizure is a forensic software toolkit from Paraben that provides the means to 

extract data from mobile devices running Palm OS, Windows CE, and RIM OS. The 

case file has a proprietary format and can be output in an HTML file format. 

Acquisition occurs via a cable, IrDA, or Bluetooth interface; no additional hardware is 

necessary. Although the tool can be used with smart phones, the toolkit is oriented 

toward non-cellular devices. PDA Seizure’s features include the ability to perform a 

logical acquisition and, for certain devices, a physical acquisition, providing views of 

internal memory as well as individual files and databases. An MD5 message digest is 

created for individual data objects and the overall case file. Additionally, the case 

files are encrypted to prevent tampering and data modification. PDA Seizure provides 

examiners with the ability to create customized reports and report notes, import 

archived case files, bookmark significant findings, and search the acquired data. 

 Pilot-link is a non-forensic open source software suite originally developed for the 

Linux community as a means to transfer data between Linux hosts and Palm OS 

devices. Pilot-link provides the ability to extract RAM, ROM and individual files 

present on Palm OS devices. Two programs of interest to forensic examiners are pigetram and pi-getrom, which respectively retrieve the physical contents of RAM and 

ROM from a device. Another useful program is pilot-xfer, which provides a means to 

acquire the contents of a device logically. Neither an overall case file, integrity hash 

computation, nor customizable report facility are provided. 

 The forensic version of Oxygen Phone Manager (OPM) from Oxygen Software is a 

variant of the phone management product of the same name, which works mainly on 

Nokia phones. The forensic version differs from the non-forensic version by 

prohibiting modification to the target device. OPM provides examiners with the 

ability to extract data from cellular devices operating over the GSM network. OPM 

does not allow examiners to export an overall case file; however, acquired data is 

stored in multiple files (e.g., Phonebook, SMS, and Gallery) that correlate with the 

related function. OPM does not protect acquired data via hashing functions. 

Acquired data can be exported out into various supported format types. 

 A forensic version of Oxygen Phone Manager for Symbian devices, from Oxygen 

Software, also exists. The tool targets mobile phones and smart phones that use the 

Symbian OS. The above-mentioned characteristics of OPM apply equally to OPM 

for Symbian devices. 

 BitPIM is open source software available under the GNU General Public License. It 

is a phone management program that allows the viewing and manipulation of data 

primarily from CDMA cell phones by various manufacturers. A read-only check box 

is provided to disable writing to the phone when used for acquisition. BitPIM does 

not allow examiners to export or save an overall case file; however, acquired data is 

stored in multiple files (e.g., Phonebook, SMS, and Filesystem) and can be exported 

in common formats for reporting purposes. BitPIM does not protect acquired data via 

hashing functions. 

 Phone flashing tools are available for different families of cell phones from a variety 

of sources. These tools are intended to load new versions of software into the 

memory of a phone as a means of repair and upgrade. While they do provide the 

means to acquire handset memory physically, they are strictly non-forensic in nature, 

19
Guidelines on Cell Phone Forensics 

have little documentation and support, and do not compute an integrity hash over 

acquired data. Phone flashers should be used with extreme caution only after 

sufficient testing and study is done. Mapping the layout of recovered memory, 

identifying objects, and decoding data is time-consuming to perform manually. 

However, the process can recover such things as phone locks, deleted data, and other 

useful information normally not recoverable through a logical acquisition, such as 

historical information (e.g., the IMSI of previous (U)SIMs used with the phone). 

3.3 Integrated Toolkits 

Several toolkits incorporate the capabilities of both (U)SIM and handset tools under a unified 

framework. One advantage for those devices that involve (U)SIMs is that the results of 

handset and (U)SIM examinations can appear within the same generated report. This 

advantage disappears if another tool is used for either device, such as in the case where a 

particular handset might not be supported by the tool. 

 Cell Seizure from Paraben is a forensic software toolkit that provides the means to 

extract data from GSM and non-GSM (i.e., CDMA, TDMA) cellular devices and 

(U)SIMs. The case file is in a proprietary format and case data can be output in either 

an ASCII or HTML format. Acquisition occurs via a cable, IrDA, or Bluetooth 

interface. Cell Seizure also allows direct acquisition of (U)SIM cards with the 

included RS-232 SIM card reader. The package comes complete with cables and 

drivers for supported phones, as well as the application software. Cell Seizure’s 

features include the ability to perform a logical and physical acquisition, providing 

views of internal memory as well as individual files and databases. MD5 and SHA1 

hash values are created for individual data objects and an overall message digest of the 

acquired case data is calculated. The case file is also encrypted, preventing tampering 

and data modification. Cell Seizure provides examiners with the ability to create 

customized reports and report notes, import archived case files, bookmark significant 

findings, and search the acquired data. 

 CellDEK from Logicube Inc. is designed to acquire data from cell phones operating 

over GSM and non-GSM networks, PDAs, SIM cards and flash-based media. The 

CellDEK terminal contains an embedded touch-screen PC, data cables for various 

devices, a PC/SC SIM card reader, and a write-protected memory card reader, 

packaged in a rugged, watertight carrying case. The unit provides the ability to 

connect to cell phones and PDAs via a cable, Bluetooth or IrDA connection. 

Acquisitions are stored on the CellDEK’s hard disk and can be moved or backed up to 

a USB thumb drive. All data is individually hashed using the MD5 algorithm to 

ensure that the integrity of the data can be verified. CellDEK generates report files in 

an HTML format, containing all of the data recovered. Reports can be customized 

with company logos and case details when entered by the examiner before acquiring 

the device. 

 GSM .XRY is a forensic software toolkit from Micro Systemation that provides the 

means to extract data from GSM and non-GSM (i.e., CDMA) cellular devices and 

SIM/USIM cards. A USB dongle is needed to operate the software. The GSM .XRY 

hub provides an interface for the dongle and device cables, and interfaces for 

Bluetooth and IrDA. The package comes complete with cables and drivers for 

supported phones, as well as the application software. Data acquired from cell phone 

20
Guidelines on Cell Phone Forensics 

devices are stored in the proprietary .XRY format and cannot be altered, but can be 

exported into external formats and viewed with third-party applications. GSM .XRY 

encrypts case data and compares digital signatures for consistency when previously 

stored case data is re-opened for examination. Additionally, case files can be locked 

and password protected, providing an extra layer of security against alteration. GSM 

.XRY provides the ability to create customized reports, import archived case files, and 

perform searches on the acquired data. 

 MOBILedit! Forensic from Compelson Labs is an application that provides the means 

to acquire data logically from GSM or non-GSM (i.e., CDMA) devices and SIM 

cards. The tool is based on the non-forensic phone management software of the same 

name. Phone data can be acquired via cable, Bluetooth, or IrDA, and via a PC/SC 

compatible card reader for SIMs. Acquired data is stored in a proprietary case file 

format and can be exported to XML. Mobiledit! provides the ability to create 

customized reports, import archived case files and perform search queries on specific 

folders. Mobiledit! does not protect acquired data via hash value computations. 

 PhoneBase 2 from Envisage Systems Ltd. provides the means to acquire data from 

GSM and non-GSM cellular devices and data contained on (U)SIMs. PhoneBase 2 

uses the MOBILedit! acquisition engine for its handset support, but complements that 

with its own facility for (U)SIM acquisition. A USB dongle is needed to operate the 

software. Data can be acquired via cable, Bluetooth, IrDA or a PC/SC compatible 

card reader for SIMs. Acquired data is stored in a common database format and 

protected from tampering via a PhoneBase security (pbs) file. PhoneBase 2 provides 

examiners with the ability to create customized reports, import archived case files and 

perform search queries over multiple cases. 

 Secure View is a commercial forensic tool from Susteen, derived from the company’s 

Datapilot phone management software, which provides examiners with the ability to 

extract data from cellular devices operating over GSM and non-GSM (i.e., CDMA, 

TDMA) networks. Recent versions of Secure View also can acquire SIM card data 

using a PC/SC-compatible reader. Secure View does not allow examiners to export 

an overall case file; however, acquired data is stored in multiple files (e.g., Address 

book, SMS, Graphics, and Audio) that correlate with the related function. The 

package comes complete with cables and drivers for supported phones, and the 

application software. Secure View does not protect acquired data via hashing 

functions. However, data can be password protected, allowing only authorized 

access. Secure View provides a search engine that allows a subset of the acquired 

data to be analyzed and the ability to import pre-existing case data. 

 TULP2G (2nd generation) is an open source forensic software tool from the 

Netherlands Forensic Institute that provides the means to acquire data from cellular 

GSM and non-GSM (i.e., CDMA) devices and SIMs [Bos05]. Data can be acquired 

via a cable, Bluetooth or IrDA interface. Reading SIMs requires a PC/SC-compatible 

smart card reader. TULP2G generates a set of raw data in XML format, which can be 

converted to a readable format using embedded XSL stylesheets. SHA1 and MD5 

hashes are created over the entire case file, ensuring the integrity of acquired data. 

TULP2G provides the ability to create a report over selected data elements or the 

entire case file and import archived case files. 

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Guidelines on Cell Phone Forensics 

Tool Segregation: With the use of multiple forensic tools, the possibility exists for conflicts to 

occur among certain ones. Resolving such conflicts can sometimes be onerous and time 

consuming, and may need to be repeated across a number of forensic workstations. One 

method to avoid these problems is to use a product such as VMware to create a virtual machine 

environment on each forensic workstation for the tool to execute. 

Each software tool and its operating system can be installed in a distinct virtual machine 

environment, independently from other tools, effectively segregating each tool from the others. 

Compatible collections of tools could also be isolated from incompatible tools this way. Cloning 

the virtual machine with the installed tool or tool collection can be done to baseline a configuration 

for distribution and execution at other workstations’ virtual machines, establishing a common 

computational environment throughout an organization while simplifying the configuration 

process. Since multiple independent virtual machines can run simultaneously on a single 

workstation, several tools or tool collections that otherwise would be incompatible are readily 

supported. 

3.4 Capabilities 

Forensic software tools strive to address a wide range of applicable devices to handle the most 

common investigative situations with modest skill level requirements and keep the device 

intact. More difficult situations, such as the recovery of deleted data, require more specialized 

tools and expertise, and often disassembly of the device [Wil05]. The range of support 

provided, including phone cables and drivers, product documentation, (U)SIM readers, and 

updates, can vary significantly among products. The features offered such as searching, 

bookmarking, and reporting capabilities can also vary considerably. 

Quality measures should be applied when first choosing a tool to ensure its acceptability and 

reapplied when updates or new versions of the tool become available to uphold consistency. 

Validating a tool entails defining a comprehensive test data set, loading it onto the device using 

the same methods a user would, and following procedures to acquire and recover the test data 

[Goo03, Aye05, Aye07]. While tool validation can be time consuming to perform, it is a 

necessary standard quality practice to follow. Forensic specialists should also receive adequate 

up-to-date training in the tools and procedures to employ, as a quality measure. 

Mobile phone forensic tools are in their early stages of maturity. They typically have 

limitations in both the breadth of the devices supported and the depth of evidence recovered. 

Subtle errors may also be encountered in their use. For example, a data item displayed on 

screen may vary from the same item appearing in a generated report. Practice and experience 

with a tool can normally compensate for such problems and procedures can be adapted 

accordingly. Occasionally, new versions of a tool may fail to perform as well as a previous 

one. 

The most important characteristic of a forensic tool is its ability to maintain the integrity of the 

original data source being acquired and also that of the extracted data. The former is done by 

blocking or otherwise eliminating write requests to the device containing the data. The latter is 

done by calculating a cryptographic hash of the contents of the evidence files created and 

recurrently verifying that this value remains unchanged throughout the lifetime of those files. 

Preserving integrity not only maintains credibility from a legal perspective, but it also allows 

any subsequent investigation to use the same baseline for replicating the analysis. 

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Guidelines on Cell Phone Forensics 

Forensic Hash: A forensic hash is used to maintain the integrity of an acquisition by computing a 

cryptographically strong, non-reversible value over the acquired data. After acquisition, any 

changes made to the data can be detected, since a new hash value computed over the data will 

be inconsistent with the old value. For non-forensic tools, hash values should be created 

manually using a tool such as sha1sum or md5sum and retained for integrity verification. Even 

tools labeled as forensic tools may not compute a cryptographic hash, and an integrity hash 

should be computed manually. 

Note that mobile devices are constantly active, updating information (e.g., the device clock) 

continuously. Some devices, stemming mainly from a PDA heritage, are active even when turned 

off [Bur02]. Therefore, back-to-back acquisitions of a device will be slightly different and produce 

different hash values when computed over all the data. However, hash values computed over 

selected portions of the data, such as individual files and directories, generally remain constant. 

Only a few forensic tools offer more granular hash computation of files and directories. Some 

forensic tools also do not notify the user automatically about hash inconsistencies, placing the 

onus on the forensic specialist to check the hash values manually. 

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Guidelines on Cell Phone Forensics 

4. Procedures and Principles 

Investigations and incidents are handled in various ways depending upon the circumstances of 

the incident, the gravity of the incident, and the preparation and experience of the investigation 

team. Digital investigations are comparable to crime scenes where investigative techniques 

used by law enforcement have been applied as a foundation for the creation of procedures used 

when dealing with digital evidence. This chapter provides an overview of various procedural 

models and principles that have been proposed. 

4.1 Roles and Responsibilities 

Whatever the type of incident, the various types of roles involved are similar. Planning should 

address how existing personnel fulfill these roles when responding and participating in an 

investigation. A set of generic roles and associated responsibilities are given below as an 

example. They include First Responders, Investigators, Technicians, Forensic Examiners, 

Forensic Analysts, and Evidence Custodians. Organizations may need to blend together these 

roles to match their method of operation and level of staffing. In given situations, a single 

individual may also be expected to perform more than one role. Nevertheless, distinguishing 

distinct roles is a useful way to identify associated responsibilities and ensure that the overall 

scope of activities is complete and sufficient. 

First Responders are trained personnel who arrive first on the scene of an incident, provide an 

initial assessment, and begin the appropriate level of response. The responsibilities of First 

Responders are to secure the incident scene, call for the appropriate support needed, and assist 

with evidence collection. 

Investigators plan and manage preservation, acquisition, examination, analysis, and reporting 

of electronic evidence. The Lead Investigator is in charge of making sure that activities at the 

scene of an incident are executed in the right order and at the right time. The Lead Investigator 

may be responsible for developing the evidence, preparing a case report, and briefing any 

findings and determinations to senior officials. 

Technicians carry out actions at the direction of the Lead Investigator. Technicians are 

responsible for identifying and collecting evidence and documenting the incident scene. They 

are specially trained personnel who seize electronic equipment and acquire digital images 

resident within memory. More than one technician is typically involved in an incident, 

because different skills and knowledge are needed. Sufficient expertise should be available at 

the scene to address all distinct digital apparatus involved in the incident. 

Evidence Custodians protect all evidence gathered that is stored in a central location. They 

accept evidence collected by Technicians, ensure it is properly tagged, check it into and out of 

protective custody, and maintain a strict chain of custody. 

Forensic Examiners are specially trained personnel who reproduce images acquired from 

seized equipment and recover digital data. Examiners make visible evidential information on 

the device. Examiners may also acquire more elusive data using highly specialized equipment, 

intensive reverse engineering, or other appropriate means unavailable to Forensic Technicians. 

Having individuals serve as both an Investigator and a Forensic Examiner in an investigation 

should generally be avoided.

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Guidelines on Cell Phone Forensics 

Forensic Analysts evaluate the product of the Forensic Examiner for its significance and 

probative value to the case. 

4.2 Evidential Principles 

As a backdrop to any investigation, basic principles have been proposed for dealing with 

digital evidence. Digital evidence by its very nature is extremely fragile, especially that found 

on cell phones. A phone’s contents and the evidence it contains can be affected or even lost 

any time it is on. Digital evidence has two aspects: the physical components, peripherals, and 

media, that may contain data, and the data extracted from those sources. Each has associated 

chain of custody issues. The Association of Chief Police Officers (ACPO) Good Practice 

Guide for Computer based Electronic Evidence [ACPO] suggests four principles when dealing 

with digital evidence, summarized here: 

 No actions performed by investigators should change data contained on digital 

devices or storage media that may subsequently be relied upon in court. 

 Individuals accessing original data must be competent to do so and have the ability to 

explain their actions. 

 An audit trail or other record of applied processes, suitable for replication of the 

results by an independent third-party, must be created and preserved, accurately 

documenting each investigative step. 

 The person in charge of the investigation has overall responsibility for ensuring the 

above-mentioned procedures are followed and in compliance with governing laws. 

The Proposed Standards for the Exchange of Digital Evidence [IOCE] suggest a similar set of 

principals for the standardized recovery of computer-based evidence: 

 Upon seizing digital evidence, actions taken should not change that evidence. 

 When it is necessary for a person to access original digital evidence, that person must 

be forensically competent. 

 All activity relating to the seizure, access, storage, or transfer of digital evidence must 

be fully documented, preserved, and available for review. 

 An individual is responsible for all actions taken with respect to digital evidence while 

the digital evidence is in their possession. 

 Any agency that is responsible for seizing, accessing, storing, or transferring digital 

evidence is responsible for compliance with these principles. 

The above sets of principles aim to ensure the integrity and accountability of digital evidence 

through its entire life cycle. Proper handling of evidence is always vital for it to be admissible 

in judicial proceedings. However, different standards may apply to different types of 

investigations. The degree of training and expertise required to execute a forensic task largely 

depends on the level of evidence required in the case [Pur]. For example, using a forensic 

software tool requires modest skill levels to acquire active data, compared with those required 

25
Guidelines on Cell Phone Forensics 

to remove a memory chip and recover data contents, which includes both active and deleted 

data. 

The Daubert method, a set of standards that serve as a guide when dealing with evidence in a 

court of law, proposes several reliability factors, which should be kept in mind when applying 

and reporting on a scientific technique that is being used in a forensic examination [Oco04]: 

 Testability – Has the scientific theory or technique been empirically tested? 

According to K. Popper (1989) in The Growth of Scientific Knowledge, "the criterion 

on the scientific status of a theory is its falsifiability, refutability, and testability." 

 Acceptance – Has the scientific theory or technique been subjected to peer review 

and publication? This ensures that flaws in the methodology would have been 

detected and that the technique is finding its way into use via the literature. 

 Error Rate – What is the known or potential error rate? Scientific measures 

generally have associated error rates, which can be estimated with a fair amount of 

precision. Known threats exist against the validity and reliability in any test 

(experimental and quasi-experimental) of a theory. 

 Credibility – What is the expert's qualifications and stature in the scientific 

community? Does the technique rely upon the special skills and equipment of one 

expert, or can it be replicated by other experts elsewhere? 

 Clarity – Can the technique and its results be explained with sufficient clarity and 

simplicity so that the court and the jury can understand its plain meaning? This 

criterion is implicitly assumed to be incorporated in Daubert. 

The procedures used to acquire evidence affect its admissibility. This applies as well to 

evidence acquired from mobile phones using forensic software tools [Mcc06]. Even outside of 

law enforcement investigations, evidence should be collected in a manner that is suitable for 

admissibility in court. It may not be obvious when an investigation is initiated, for example, 

when a computer security incident is first detected, that court action may ensue. Important 

evidence might be overlooked, improperly handled, or accidentally destroyed before the 

seriousness of the incident is realized. 

4.3 Procedural Models 

The Electronic Crime Scene Investigation – A Guide for First Responders, produced by the 

U.S. Department of Justice [DOJ01], offers the following suggestions when approaching a 

digital crime scene. 

 Securing and Evaluating the Scene – Steps should be taken to ensure the safety of 

individuals and to identify and protect the integrity of potential evidence. 

 Documenting the Scene – Create a permanent record of the scene, accurately 

recording both digital-related and conventional evidence. 

 Evidence Collection – Collect traditional and digital evidence in a manner that 

preserves their evidentiary value. 

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Guidelines on Cell Phone Forensics 

 Packaging, Transportation, and Storage – Take adequate precautions when 

packaging, transporting, and storing evidence, maintaining chain of custody. 

Incident Response [Man01], an “Incident Response Methodology” proposes the following 

phases when encountering an incident or performing a digital investigation. 

 Pre-incident preparation – Through training and education, gain an understanding 

on how to respond to an incident. 

 Detection of incidents – Develop techniques on how to detect suspect activities. 

 Initial Response – Confirm that an incident has occurred and obtain volatile 

evidence. 

 Response strategy formulation – Respond to incident based upon knowledge of all 

known facts collected from the Initial Response phase. 

 Duplication (forensic backups) – Based upon the scenario, either create a physical 

forensic image or do a live retrieval of evidence. 

 Investigation – Determine what happened, who did it and how the incident can be 

prevented in the future. 

 Security measure implementation – Apply security measures to isolate and contain 

infected systems. 

 Network monitoring – Monitor network traffic for ongoing or additional attacks. 

 Recovery – Restore the affected system to a secure, operational state. 

 Reporting – Document all of the details and investigative steps taken throughout the 

incident. 

 Follow-up – Learn from the incident by reviewing how and why it happened and 

make necessary adjustments. 

Research conducted at the U.S. Air Force proposes the following steps when dealing with a 

forensic investigation [Rei02]. 

 Identification – Recognize and determine the type of incident. 

 Preparation – Prepare tools, techniques, search warrants, authorizations, and 

management approval. 

 Approach Strategy – Maximize untainted evidence collection while minimizing the 

impact upon the victim. 

 Preservation – Isolate, secure, and preserve the state of physical and digital evidence. 

 Collection – Record the physical scene and duplicate digital evidence. 

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Guidelines on Cell Phone Forensics 

 Examination – Search for evidence relating to the suspected crime. 

 Analysis – Determine significance, reconstruct fragments of data, and draw 

conclusions based on the evidence found. The Analysis phase may go through 

numerous iterations until a theory has been supported. 

 Presentation – Summarize and provide an explanation of conclusions. 

 Return Evidence – Ensure physical and digital property is returned to the proper 

owner. 

Although developed primarily for computer systems, each of the above procedural models and 

the evidential principles discussed contain important points that should be considered when 

dealing with digital evidence on cell phones. Because every investigation is distinct with its 

own unique set of circumstances, a single definitive procedural approach is difficult to 

prescribe. Nevertheless, most models touch on the same key areas, though stressing different 

aspects. The remaining chapters of this guide follow a simple framework of four topical areas: 

obtaining an exhibit, making a forensic copy of its contents, obtaining evidence from the 

forensic copy, and reporting on the evidence obtained and process used. They are respectively 

referred to within this document as preservation, acquisition, examination and analysis, and 

reporting. 

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Guidelines on Cell Phone Forensics 

5. Preservation 

Evidence preservation is the process of seizing suspect property without altering or changing 

the contents of data that reside on devices and removable media. It is the first step in digital 

evidence recovery. The chapter begins with a generic introduction to preservation, and then 

provides more specific guidance about cell phones. 

Preservation involves the search, recognition, documentation, and collection of electronicbased evidence. In order to use evidence successfully, whether in a court of law or a less 

formal proceeding, it must be preserved. Failure to preserve evidence in its original state could 

jeopardize an entire investigation, potentially losing valuable case-related information. 

The DOJ’s Electronic Crime Scene Investigation report covers this subject in detail [DOJ01]. 

The guide offers principles, policies, and procedures to follow when encountering a digital 

evidence scene. The reader is directed to that report for additional information. The following 

is a summary of the key points to observe. 

 Securing and Evaluating the Scene 

 Ensure the safety of all individuals at the scene. 

 Protect the integrity of traditional and electronic evidence. 

 Evaluate the scene and formulate a search plan. 

 Identify potential evidence. 

 All potential evidence should be secured, documented, and/or photographed. 

 Conduct interviews. 

 Documenting the Scene 

 Create a permanent historical record of the scene.

 Accurately record the location and condition of computers, storage media, other 

digital devices, and conventional evidence. 

 Document the condition and location of the computer system, including power 

status of the computer (on, off, or in sleep mode). 

 Identify and document related electronic components that will not be collected. 

 Photograph the entire scene to create a visual record as noted by the first 

responder.

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Guidelines on Cell Phone Forensics 

 Collecting Evidence 

 Handle computer evidence, whether physical or digital, in a manner that preserves 

its evidentiary value. 

 Recover non-electronic evidence (e.g., written passwords, handwritten notes, 

blank pads of paper with indented writing, hardware and software manuals, 

calendars, literature, text or graphical computer printouts, and photographs). 

 Packaging, Transporting, and Storing Evidence 

 Take no actions to add, modify, or destroy data stored on a computer or other 

media. 

 Avoid high temperatures and humidity, physical shock, static electricity, and 

magnetic sources. 

 Maintain chain of custody of electronic evidence, documenting its packaging, 

transportation and storage. 

 Packaging Procedure 

 Properly document, label, and inventory evidence before packaging. 

 Pack magnetic media in antistatic packaging (paper or antistatic plastic 

bags). 

 Avoid folding, bending, or scratching computer media such as diskettes, 

CD-ROMs, removable media, etc. 

 Properly label evidence containers. 

 Transportation Procedure 

 Avoid magnetic sources (e.g., radio transmitters, speaker magnets). 

 Avoid conditions of excessive heat, cold, or humidity while in transit. 

 Avoid shock and excessive vibrations. 

 Storage Procedures 

 Ensure evidence is inventoried in accordance with authoritative policies. 

 Store evidence material in a secure area away from temperature and 

humidity extremes. 

 Protect evidence material from magnetic sources, moisture, dust, and 

other harmful particles or contaminants. 

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Guidelines on Cell Phone Forensics 

The Good Practice Guide for Computer Based Electronic Evidence [ACPO] suggests the 

following procedures when handling cell phones: 

 Before handling, consider what other types of evidence, such as DNA or fingerprints, 

are needed from the phone and follow the appropriate handling procedures. 

 Switching the phone off is advisable, because of the potential for loss of data if either 

the battery expires or network activity occurs, causing call logs or other recoverable 

data to be overwritten. 

 If the phone remains on for some purpose, it should be kept charged and not tampered 

with, then switched off before transport. 

 To prevent accidental operation in transit, the phone should be packaged in a rigid 

container, secured with support ties. 

 The container should be placed into an evidence bag, sealed to restrict access, and the 

labeling procedures completed for the exhibit. 

The remaining sections of this chapter provide supplemental information related to cell 

phones, following the paradigm of Securing and Evaluating the Scene, Documenting the 

Scene, Collecting Evidence, and Packaging, Transporting, and Storing Evidence. 

5.1 Securing and Evaluating the Scene 

Ensuring that the proper authorizations (e.g., a search warrant or consent from the owner) are 

in place is paramount for beginning an investigation. When searching a site, the team should 

proceed cautiously. Incorrect procedures or improper handling of a mobile phone during 

seizure can cause loss of digital evidence. Moreover, traditional forensic measures, such as 

fingerprints or DNA testing, may need to be applied to establish a link between a mobile phone 

and its owner or user, or for other reasons. If the device is not handled properly, physical 

evidence can be easily contaminated and rendered useless. 

Alertness to device characteristics and issues (e.g., memory volatility) and familiarity with 

associated accessories (e.g., media, cables, cradles, and power adapters) are essential. For cell 

phones, sources of evidence include the device, (U)SIM, and media. Associated peripherals, 

cables, cradles, power adapters, and other accessories are also of interest. The surrounding 

area and rooms, other than where a device is found, should be searched to ensure related 

evidence is not overlooked. To avoid unwanted interaction with devices found on the scene, 

consideration should be given to turning off wireless interfaces, such as Bluetooth and WiFi 

radios, on equipment brought into the search area. 

Equipment associated with the cell phone, such as removable media, (U)SIMs, or even 

personal computers possibly synched with it, may prove more valuable than the phone itself. 

Removable media varies from the size of a fingernail to that of a postage stamp, and can be 

easily hidden and difficult to find. Most often, removable memory cards are identifiable by 

their distinctive shape and the presence of pins, pin receptacles, or contacts located on their 

body, used to establish an electrical interface with the device. 

31
Guidelines on Cell Phone Forensics 

 

When interviewing the owner or user of a mobile device, consider requesting any security 

codes or passwords needed to gain access to its contents. For example, a PIN can be set on 

GSM phones and some of them also have lock codes that can be set in conjunction with or in 

lieu of the PIN. Suspects should never be allowed to handle mobile phones or other mobile 

devices. Many phones have master reset codes that clear the contents of the phone to the 

original factory conditions. Removing the battery can also cause the contents of some devices 

to be lost, such as certain smart phones. 

Phones may be found in a compromised state that can complicate seizure, such as immersed in 

a liquid. In the case of liquids, the battery should be removed to prevent electrical shorting. 

The remainder of the phone should be sealed in an appropriate container filled with the same 

liquid for transport to the lab, provided the liquid is not caustic. Some compromised states, 

such as blood contamination or use with explosives (i.e., as a bomb component) can pose a 

danger to the technician collecting evidence. In such situations, a specialist should be 

consulted for specific instructions or assistance, if doubt exists on how to proceed.11

Mobile phones and associated media may be found in a damaged state, caused by accident or 

deliberate action. Devices or media with visible external damage do not necessarily prevent 

the extraction of data from them. Damaged equipment should be taken back to the lab for 

closer inspection. Repairing damaged components on a mobile phone and restoring the device 

to working order for examination and analysis may be possible. Undamaged memory 

components may also be removed from a damage device and their contents recovered 

independently. 

Legal advisors should be contacted for assistance, if needed, with the following two critical 

legal considerations [DOJ04]: 

 Determining the extent of the authority to search and what additional legal process 

may be necessary to continue the search (e.g., warrant, amended consent form), if 

evidence is located that was not authorized in the original search authority. 

 Identifying possible concerns related to applicable local policies and laws, and 

International, Federal, or State statutes, such as the Electronic Communications 

Privacy Act of 1986 (ECPA) and the Cable Communications Policy Act (CCPA). 

5.2 Documenting the Scene 

Evidence must be accurately accounted for and identified. Non-electronic evidence such as 

invoices, manuals, and packaging material may provide useful information about the 

capabilities of the device, the network used, account information, and unlocking codes for the 

PIN. The labeling process should document the case number, a brief description, signature, 

and the date and time the evidence was collected. Photographing the crime scene in 

conjunction with documenting a report of the state of each digital device and computer 

encountered (personal computers may contain useful data that has not been synchronized with 

the owner’s mobile phone) can be helpful, particularly if questioned about the environment 

later [Kru01]. 

11 The Netherlands Forensic Institute’s procedures for preservation can be found at 

http://www.holmes.nl/MPF/FlowChartForensicMobilePhoneExamination.htm. 

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Guidelines on Cell Phone Forensics 

A record of all visible data should be created. All digital devices, including mobile phones, 

which may store data, should be photographed along with all peripherals cables, cradles, 

power connectors, removable media, and connections. Avoid touching or contaminating the 

phone when photographing it and the environment where found. If the device’s display is in a 

viewable state, the screen’s contents should be photographed and, if necessary, recorded 

manually, capturing the time, service status, battery level, and other displayed icons. Other 

characteristics such as LED activity (e.g., blinking), physical condition, physical connectivity, 

or visible identifiers should also be noted. Having an individual in charge to perform evidence 

custodian duties at the scene, alongside a partner responsible for documentation of evidence, is 

desirable during the collection phase [Kru01]. 

Actions taken on the system to view and record other volatile data not under display at the time 

can affect the state of the device. For example, launching an application on a smart phone can 

overwrite parts of memory. Furthermore, it risks activating Trojan horse code hidden within 

the application or accidentally hitting an incorrect key sequence, and causing unintended 

effects. 

The chain of custody procedure is a simple yet effective process of documenting the complete 

journey of evidence through the lifecycle of the case. Carefully maintaining the chain of 

custody not only protects the integrity of evidence, but also makes if difficult for someone to 

argue that the evidence was tampered with [Kru01]. The documentation should answer the 

following questions: 

 Who collected it? (i.e., devices, media, associated peripherals, etc.) 

 How and where? (i.e., how was the evidence collected and where was it located) 

 Who took possession of it? (i.e., individual in charge of seizing evidence) 

 How was it stored and protected in storage? (i.e., evidence-custodian procedures) 

 Who took it out of storage and why? (i.e., on-going documentation of individual’s 

name and purpose for checking-out evidence) 

Documentation to all of the above questions must be maintained and filed in a secure location 

for current and future reference. 

5.3 Collecting the Evidence 

The Mobile Phone Forensics Sub-Group of the Interpol European Working Party on IT Crime 

has identified how the ACPO Principles of Evidence apply to seizure of mobile phones 

[INT06]. Some key implications for proper collection are summarized below. 

Isolating the phone from other devices used for data synchronization is important to keep new 

data from contaminating existing data. If the device is found in a cradle or connected with a 

computer via a cable, pulling the plug from the back of the computer eliminates data transfer or 

synchronization overwrites. The phone should be seized along with the cradles and cables 

found. Media cards, (U)SIMs, and other hardware residing in the phone should not be 

removed. Also, seizing the computer that was connected to the phone allows the possibility to 

acquire synchronized data from the hard disk that might not be obtained from the phone. Any 

33
Guidelines on Cell Phone Forensics 

associated hardware such as media cards, (U)SIMs, power adapters, device sleeves, or 

peripherals, should be seized along with related materials such as product manuals, packaging, 

and software. 

Isolating the phone from the radio network is important to keep new traffic, such as SMS 

messages, from overwriting existing data, if the phone is turned on when found. Besides the 

risk of overwriting potential evidence, the question may arise whether data received on the 

phone after seizure is within the scope of the original authority granted. Add-on programs, 

such as LockMe12 and OmaiProtect13, are also available that enable the phone lock to be set 

remotely upon receipt of a properly formatted message. Moreover, vulnerabilities may exist 

that can be exploited. For example, a malformed message sent to a Nokia 6210 phone has 

been shown to disable it completely, much like the a malformed ICMP packet known as the 

“ping of death” did to older Windows computers [Ley01]. 

Two basic methods for isolating the phone from radio communication and preventing these 

problems are to “Turn (the) device off at the point of seizure” or to “Place (the) device in a 

shielded container/bag” [INT06]. Alternatively, if the device has an “Airplane Mode” 

function, the setting could be enabled [Bur02]. Each method has certain drawbacks, however. 

 Turning off the phone may activate authentication codes (e.g., SIM PIN and/or 

handset security codes), which are then required to gain access to the device, 

complicating acquisition and delaying examination. 

 Keeping the phone on, but radio isolated, hastens battery life due to increased power 

consumption as it tries unsuccessfully to connect to a network, raising its signal 

strength to the maximum. After some period, failure to connect to the network may 

cause certain phones to reset or clear network data that otherwise would be useful if 

recovered [Smi05]. Containers attenuate the radio signal, but not necessarily 

eliminate it completely, allowing the possibility of communications being established 

with a cell tower, if in its immediate vicinity. The risk of improperly sealing the radio 

isolation container and unknowingly allowing access to the cell network also exists. 

 Enabling “Airplane Mode” requires interaction with the phone via the keypad, which 

poses some risk – less so, if the technician is familiar with the device in question and 

documents the actions taken (e.g., on paper or on video). 

If user data resides in battery-dependent volatile memory, expiration of the battery would be 

disastrous. Before collecting such a mobile phone, the power state must be considered. For 

example, the device may be fully charged, receiving power from a charger or cradle plugged 

into an outlet, or extremely low on battery power. Steps must be taken to maintain the battery 

level at an appropriate level until a successful acquisition takes place. This may be especially 

challenging if the device needs to be radio isolated, requiring it to be placed in the container 

together with a portable source of supplemental power (e.g., a disposable charger such as 

 

12 Product information is available at http://www.allaboutsymbian.com/software/item/LockMe1.php. 

13 Product information is available at: http://shop.mysymbian.com/PlatformProductDetail.jsp?siteId=695&jid=9XE2C5FBA428B2D242AXA4AB13E866AX&platform

Id=4&productType=2&catalog=0&sectionId=0&productId=187426. 

34
Guidelines on Cell Phone Forensics 

 

cellboost14 or a battery-powered charger15), after full charging. If sufficient power cannot be 

supplied, consideration should be given to switching off the phone to preserve battery life, 

documenting the current device state and noting the time and date of the shutdown. 

Charging may also be required post-examination, if reexamination of the original device is 

anticipated due to expected challenges to the results of the initial examination. Otherwise, 

replication of results cannot be achieved once battery depletion causes loss of volatile memory 

content. Even when the phone is isolated, content changes may occur on an active device that 

could be undesirable, such as the execution of a scheduled script that purges old data. 

To conserve power, some smart phones are normally configured to enter energy savings mode 

and shut off the display after a short period of inactivity. Some phones also shut themselves 

off if the battery level drops below a certain threshold to protect data stored in volatile 

memory, which defeats the original purpose of keeping it turned on. Keeping a device in the 

active state is troublesome, requiring periodic interaction with the device. Anecdotal evidence 

suggests that built-in and add-on protections, such as user authentication and content 

encryption, are not employed for the vast majority of phones seized. If additional power 

cannot be supplied to a device and it is turned off to conserve power and preserve memory 

contents, the risk of encountering a protection mechanism when turned on again should overall 

be low. Moreover, authentication mechanisms, such as passwords, typically cannot be 

deactivated without first satisfying the mechanism (e.g., supplying the correct password). For 

these reasons, procedures for some organizations may recommend turning off certain classes 

of phones, if found powered on. 

“A small number of mobile communication devices ... use alkaline batteries as a power 

source. Consideration should be given to replacing the batteries prior to transit to minimize the 

risk of data loss due to complete battery discharge before the device reaches the examination 

unit [INT06].” Some smart phones use rechargeable batteries that are replaceable, and a fully 

charged replacement battery can be substituted, if available. Such phones keep a small charge 

to the device to maintain volatile data for a short amount of time during battery replacement. 

To prevent loss of volatile data, batteries must be replaced quickly. 

The time maintained on the phone may be set independently of that from the network. Always 

record the date and time shown on the handset, if it is turned on, and compare them with a 

reference clock, noting any inconsistencies. If the screen is dim due to power management, it 

may be necessary to press an insignificant key such as the volume key to light the screen. 

When preparing the packing labels, be sure to record the manufacturer and model of the seized 

equipment, and also its condition. The make and model may be branded on the body of the 

handset and also appear in the interior of the handset under the battery. However, do not 

remove the battery to read this information, if the phone is on. 

Caution should be exercised when handling a phone suspected of being modified, especially if 

the modifications are presumed to be done by a security-minded individual or organization. 

Certain types of modifications to the software applications and operating system of the device 

14 Product information is available at http://www.cellboost.com/us/. 

15 Product information is available at: http://www.chargetogo.com/specs.htm and 

http://www.paramountzone.com/mobile_charger.htm. 

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Guidelines on Cell Phone Forensics 

 

might affect the way it is handled. The following is a list of examples of some classes of 

modifications to consider: 

 Security Enhancements – Organizations and individuals may enhance their 

handheld devices with add-on security mechanisms. A variety of visual login, 

biometric, and token-based authentication mechanisms are available for smart phones 

to use as replacements or supplements to password mechanisms. Improper interaction 

with a mechanism could cause the device to lock down and even destroy its contents. 

This is particularly a concern with mechanisms that use security tokens whose 

presence is constantly monitored and whose disconnection from a card slot or other 

device interface is immediately acted upon. 

 Malicious Programs – A phone may contain a virus or other malicious software. 

Such malware16 may attempt to spread to other devices over wired or wireless 

interfaces, including cross platform jumps to completely different platforms such as 

Windows computers. Common utilities or functions may also be intentionally 

replaced with versions that contain software designed to alter or damage data present 

on a phone. Such Trojan-bearing programs could conditionally be activated or 

suppressed based on conditions such as input parameters or hardware key interrupts. 

Watchdog applications could also be written to listen for specific events (e.g., key 

cords or over the air messages) and carry out actions such as wiping the device clean. 

 Key Remapping – Hardware keys may be remapped to perform a different function 

than the default. A key press or combination of key presses intended for one purpose 

could launch an arbitrary program. 

5.4 Packaging, Transporting, and Storing Evidence 

Once the device is ready to be seized, the forensic specialist should seal the device in a static 

proof bag and tag it. The individual who seizes the device must sign and date the tag to initiate 

a chain of custody. The device should be secured properly to prevent keys from being pressed 

accidentally (e.g., turning the device on) when in the evidence bag. Hard containers are 

manufactured specifically for this purpose and are recommended for use.17 Radio frequency 

isolation bags are also available for attenuating a device’s radio signal and should be used with 

phones left on. An independent external power charger may be connected and placed in the 

bag with the device to keep the power level full during transit. Phones with volatile memory 

resident user data, which are left off, turned off, or in “Airplane Mode,” may be packaged to 

allow a power adaptor to be connected to the device through a hole in the evidence bag to keep 

the power level high. Rechargeable devices can usually be powered through a compatible 

cigarette-lighter adapter cable to keep charge to the device while in transit. If a power adapter 

is used in conjunction with a radio frequency isolation bag, the cable must be properly shielded 

to prevent it from serving as an antenna and nullifying the effect of the isolation bag. 

Digital devices are fragile and easily damaged. When a device is transported, it should be 

handled carefully and adequately protected from shock, breakage, and extreme temperature. 

Due to the volatile nature of some smart phones, they should immediately be checked into a 

16 For more information, see http://www.eweek.com/article2/0,1895,1750109,00.asp. 

17 For example, see http://www.forensicts.co.uk/fts-packaging.asp. 

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Guidelines on Cell Phone Forensics 

forensic laboratory to be processed and the evidence custodian should be made aware of the 

situation regarding power requirements. Battery powered devices held in storage for more 

than a few days risk power depletion and data loss, unless a process is in place to avoid this 

outcome. 

Storage facilities that hold evidence should provide a cool, dry environment appropriate for 

valuable electronic equipment. All evidence should be in sealed containers, in a secure area 

with controlled access. 

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Guidelines on Cell Phone Forensics 

6. Acquisition 

Acquisition is the process of imaging or otherwise obtaining information from a digital device 

and its peripheral equipment and media. Performing acquisition at the scene has the advantage 

that loss of information due to battery depletion, damage, etc. during transportation and storage 

is avoided. However, finding a controlled setting in which to work, having the appropriate 

equipment, and satisfying other prerequisites may not be possible at the scene, but readily 

achievable within a laboratory setting. For the purpose of discussion, a laboratory 

environment is assumed throughout this chapter. Powered on devices should be handled with 

caution in a radio frequency shielded work area or have their wireless communications 

disabled by some other means. 

Radio Isolation Techniques: A number of techniques exist for isolating a mobile phone from 

cell tower communications [INT06]. Because communications are blocked, the handset 

continues increasing its signal strength up to the maximum as it continually attempts to make 

contact. This activity significantly shortens battery life. The device should be fully charged prior to 

examination and consideration should be given to having a fixed or portable power source 

attached. 

Use a jamming or spoofing device - Emitting a signal stronger than a cell phone’s or interfering 

with the signal can render a cell phone useless. Another technique involves tricking the phone 

into thinking a “no service” signal is coming from the nearest cell tower. Because such devices 

can affect communications in the surrounding public airspace beyond the examination area, they 

are illegal in many countries. [Wyl00, NIJ05] 

Use a shielded work area - Shielding an entire work area can be an expensive but effective way 

to conduct examinations safely in a fixed location. A “Faraday tent” is a cheaper alternative that 

also allows portability. Feeding cables into the tent is problematic, however, since without proper 

isolation they can behave as an antenna, defeating the purpose of the tent. The work space can 

also be very restrictive. 

Use a shielded container - A portable shielded container can allow examinations to be conducted 

safely once the phone is situated inside. Cables into the box must be fully isolated to prevent 

network communications from occurring. 

Use a substitute (U)SIM - A substitute (U)SIM mimics the identity of the original and prevents 

network access by the handset. Such cards trick the handset into accepting them as the original 

(U)SIM. The technique allows examinations to be conducted safely at any location. 

Arrange for the network service to be disabled - The cellular carrier providing service to the device 

might be induced to disable service. The service provider or network operator must be 

determined and contacted with details identifying the service to be disabled (e.g., the equipment 

identifier, subscriber identifier, phone number). Such information is not always readily available, 

however, and the coordination and confirmation process also imposes delay. 

Acquisition should occur at a forensics laboratory once the seized equipment has arrived and 

been checked in. The forensic examination begins with the identification of the device. The 

type of device, its operating system, and other characteristics determine the route to take in 

creating a forensic copy of the contents of the device. Only a few forensic software tools 

currently exist that image certain types of phones, and no single tool presently handles the full 

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Guidelines on Cell Phone Forensics 

 

range of phones on the market [Aye05, Aye07]. The type of phone under examination, 

therefore, generally dictates which tools to use in an investigation. 

6.1 Device Identification 

To proceed effectively, devices need to be identified by the make, model, and service provider. 

This information allows examiners to select the appropriate tools for acquisition. Individuals 

may attempt to thwart specialists by altering the device to conceal its true identity. Device 

alteration could range from removing manufacturer labels to filing off logos. In addition, the 

operating system and applications may be modified or in rare situations completely replaced, 

and appear differently as well as behave differently than expected. For example, removing or 

replacing splash screens is a widely discussed modification in phone forums. 

If the phone is powered on, the information appearing on the display can sometimes help 

identify the type of phone. For example, the manufacturer’s or service provider’s name may 

appear on the display, or the screen layout may indicate the family of operating system used. 

Information such as the manufacturer’s label may be found in the battery cavity (e.g., Make, 

Model, IMEI, or ESN). Removing the battery from the cavity of a phone, even when powered 

off, can affect its state, particularly the contents of volatile memory. Most phones keep user 

data in non-volatile memory, however, with the exception of certain smart phones. If the 

phone is powered on, battery removal will power it off, possibly causing an authentication 

mechanism to trigger when again powered on. 

Other clues that allow identification of a device include such things as manufacturer logos, 

serial numbers, the cradle, and power adapter. Overall, knowing the make and model helps to 

limit the potential service providers, by differentiating the type of network the device operates 

over (i.e., GSM, non-GSM), and vice versa. Synchronization software discovered on an 

associated computer also helps to differentiate among operating system families. Further 

means of identification include the following areas: 

 Device Characteristics – The make and manufacturer of a phone can sometimes be 

identified by its observable characteristics (e.g., weight, dimensions, and form factor), 

particularly if unique design elements exist. Various Web sites contain databases of 

phones that can be queried based on selected attributes to identify a particular device 

and obtain its specifications and features.18 Coverage is considerable, but not 

extensive or complete, and may require consulting more than one repository before 

making a match. 

 Device Interface – The power connector is often specific to a manufacturer and a 

reliable aid to identification. With familiarization and experience, the manufacturers 

of certain devices can be readily identified. Similarly, the size, number of contacts, 

and shape of the data cable interface of a phone used to create a connection to a host 

computer are often specific to a particular manufacturer and may prove helpful in 

18 Several examples of such Web sites include the following: http://www.phonescoop.com/phones/finder.php, 

http://www.gsmarena.com/search.php3, and http://mobile.softpedia.com/phoneFinder. 

39
Guidelines on Cell Phone Forensics 

 

identification.19 Unfortunately, the available databases for these interfaces lack the 

broad coverage to be of assistance. 

 Device Label – For phones powered off, information obtained from within the battery 

cavity can be revealing, particularly when coupled with an appropriate database. The 

manufacturer’s label often lists the make and model number of the phone and also 

unique identifiers, such as the Federal Communications Commission Identification 

Number (FCC ID) and an equipment identifier (IMEI or ESN). The FCC and 

equipment identifiers can be found on cell phones sold in the U.S. domestic market. 

For GSM or other (U)SIM bearing phones, the (U)SIM is usually located under the 

battery and is typically imprinted with a unique identifier called the Integrated Circuit 

Card Identification (ICCID). For powered on GSM and UMTS phones, the 

International Mobile Equipment Identifier (IMEI) can be obtained by keying in 

*#06#. Similar codes exist for obtaining the Electronic Serial Number (ESN) from 

powered on CDMA phones. Various sites on the Internet offer databases for querying 

the identifier and providing information about the device. 

 The IMEI is a 15-digit number that indicates the manufacturer, model type, and 

country of approval for GSM devices. The initial 8-digit portion of the IMEI, 

known as the Type Allocation Code (TAC), gives the model and origin. The 

remainder of the IMEI is manufacturer specific, with a check digit at the end 

[GSM04]. A database lookup service is available from the GSM numbering plan 

Web site.20

 The ESN is a unique 32-bit identifier recorded on a secure chip in a mobile phone 

by the manufacturer. The first 8-14 bits identify the manufacturer and the 

remaining bits the assigned serial number. Many phones have codes that can be 

input into the handset to display the ESN. Hidden menus can also be activated on 

certain phones by placing them in “test mode” through the input of a code. 

Besides the ESN, other useful information such as the phone number of the 

device can be obtained. Manufacturer codes can be checked on-line at the 

Telecommunications Industry Association Web site.21

 The ICCID of the (U)SIM can be up to 20 digits long. It consists of an industry 

identifier prefix (89 for telecommunications), followed by a country code, an 

issuer identifier number, and an individual account identification number 

[ITU06]. The country and network operator name can be determined by the 

ICCID. If the ICCID does not appear on the (U)SIM, it can always be obtained 

with a (U)SIM acquisition tool. The GSM numbering plan Web site supports 

ICCID queries for this information22. 

19 For example, see http://www.gsm-technology.com/gsm.php/en,unlock,subpage_id,pinout.html. 

20 For more information, see http://www.numberingplans.com/?page=analysis&sub=imeinr. 

21 For more information, see http://www.tiaonline.org/standards/resources/esn/codes.cfm. 

22 For more information, see http://www.numberingplans.com/?page=analysis&sub=simnr. 

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Guidelines on Cell Phone Forensics 

 

 The first 3 characters of the FCC ID are the company code; the next 14 are the 

product code. The FCC provides a database lookup service that can be used to 

identify a device manufacturer and retrieve information about the phone, 

including photos, user manual, and radio frequency test results.23

 Reverse Lookup – If the telephone number of the phone is known, a reverse lookup 

can be used to identify the network operator (e.g., Cingular) and the originating city 

and state (e.g., Washington D.C.). For example, FoneFinder is a service to obtain 

such information by inputting the user’s area code, three-digit prefix, and the seventh 

digit of the phone number.24 The network operator’s Web site typically contains lists 

of supported phones that can be used to narrow down and possible identify the phone 

in question. Because phone numbers can be ported among service providers, in many 

situations more up-to-date information is needed. The Number Portability 

Administration Center (NPAC) provides an automated phone system for law 

enforcement agencies to determine the current service provider assigned to a number 

and obtain contact information.25 The service covers both U.S. and Canadian phone 

numbers. 

6.2 Tool Selection and Expectations 

Once the make and model of the phone are known, available manuals can be retrieved and 

studied. The manufacturer’s Web site is a good place to begin. Typing the model number 

into Google or another search engine can also reveal a significant amount of information about 

the device. As mentioned earlier, the device being acquired largely dictates the choice of 

forensic tools. The following criteria have been suggested as a fundamental set of 

requirements for forensic tools [Car02], and should be considered when a choice of tools is 

available: 

 Usability – the ability to present data in a form that is useful to an investigator 

 Comprehensive – the ability to present all data to an investigator so that both 

inculpatory and exculpatory evidence can be identified 

 Accuracy – the quality that the output of the tool has been verified and a margin of 

error ascertained 

 Deterministic – the ability for the tool to produce the same output when given the 

same set of instructions and input data 

 Verifiable – the ability to ensure accuracy of the output by having access to 

intermediate translation and presentation results 

23 For more information, see http://www.fcc.gov/oet/fccid/. 

24 For more information, see http://www.fonefinder.net/. 

25 More information about the service, including user registration, can be found at http://www.npac.com by selecting 

the Law Enforcement/911 tab at the left-hand side of the page. 

41
Guidelines on Cell Phone Forensics 

Other factors in choosing among software tools include the Daubert considerations mentioned 

earlier in section 4.2 (particularly Acceptance) and the following items: 

 Quality – technical support, reliability, and upgrade version path 

 Capability – supported feature set, performance, and richness of features with regard 

to flexibility and customization 

 Affordability – cost versus benefits in productivity 

Experimenting with various tools on test devices to find out which acquisition tools work 

efficiently with particular device types is highly recommended. Besides gaining familiarity 

with the capabilities of the tool, experimentation allows special purpose search filters and 

custom configurations to be set up before use in an actual case. In addition, any needed 

software updates from the manufacturer can be installed. 

Established procedures should guide the technical process of acquisition, as well as the 

examination of evidence. New circumstances can arise sporadically that require adjustment to 

existing procedures, and in some situations require new procedures and methods be devised. 

Recent examples include (U)SIMs being permanently bonded into the handset of certain 

phones, handsets that are capable of supporting two (U)SIMS, and phones that block logical 

acquisition ports until a connection is made with a cell tower. Procedures must be tested to 

ensure that the results obtained are valid and independently reproducible. The development 

and validation of the procedures should be documented and include the following steps 

[DOJ04]: 

 Identifying the task or problem 

 Proposing possible solutions 

 Testing each solution on an identical test device and under known control conditions 

 Evaluating the results of the test 

 Finalizing the procedure 

6.3 Memory Considerations 

A mobile phone contains various types of volatile and non-volatile memory over which several 

general categories of data can reside: storage for the operating system code, including the 

kernel, device drivers, and system libraries; memory for executing operating system 

applications and for storing and executing user applications loaded onto the device; and user 

storage for various kinds of text, image, audio, video, and other data files, including PIM 

application data. The structure of phone memory may be partitioned into fixed areas for 

certain data, such as phonebook entries, calendar entries, call logs, and SMS messages, or 

assigned dynamically from a common shared pool of memory. Memory may also be 

structured more rigorously as a formatted file system. 

The type of memory in which each category of data is stored and the memory structure 

employed vary among manufacturers and often are based on the characteristics of the 

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Guidelines on Cell Phone Forensics 

operating system used. Even for a given model of phone, data storage location assignments 

can vary somewhat between subsidized phones supplied by different network carriers, 

depending on the adaptations made for the carriers by the manufacturer. Firmware updates 

sent out by a network carrier can also affect data locations [Vam07]. 

Figure 4 illustrates the most typical arrangement in which user files reside in non-volatile 

memory, such as Flash ROM or possibly a micro hard drive, along with the operating system 

code. Since the storage is persistent, the contents are unaffected by complete power drainage. 

Volatile memory is used for dynamic storage and its contents are lost when power is drained 

from the phone. 

Figure 4: Storage Assignments 

A common alternative memory arrangement, used mainly in smart phones that have a PDA 

heritage, is shown in Figure 5. Volatile memory is used for dynamic storage and user file 

storage. Non-volatile memory is used mainly to hold the operating system code, and possibly 

PIM data or files backed up from volatile memory by the user. Completely draining power 

from the phone clears the contents of volatile memory, while non-volatile memory is 

unaffected. 

Figure 5: Alternative Storage Assignments 

A (U)SIM is similar to a mobile phone insofar as it has both volatile and non-volatile memory 

that can contain the same general categories of data as found in a mobile phone. It can be 

thought of as a trusted sub-processor that interfaces to a phone and draws power from it. The 

file system of a SIM resides in nonvolatile memory and is organized as a hierarchical tree 

structure, composed of three types of elements: the root of the file system (MF), subordinate 

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Guidelines on Cell Phone Forensics 

directory files (DF), and files containing elementary data (EF). Figure 6 illustrates the 

structure of the file system. The EFs under DFGSM and DFDCS1800 contain mainly network 

related information for different frequency bands of operation. The EFs under DFTELECOM

contain service related information. 

Figure 6: SIM File System 

Various types of digital evidence can exist in elementary data files scattered throughout the file 

system and be recovered from a (U)SIM. Some of the same information held in the (U)SIM 

may be maintained in the memory of the mobile phone and encountered there as well. Besides 

the standard files defined in the GSM specifications, a (U)SIM may contain non-standard files 

established by the network operator [Cas06]. Several general categories of evidence that can 

be found in standard elementary data files are as follows [Jan06]: 

 Service-related Information, including unique identifiers for the (U)SIM, the 

Integrated Circuit Card Identification (ICCID), and the subscriber, the International 

Mobile Subscriber Identity (IMSI) 

 Phonebook and Call Information, known respectively as the Abbreviated Dialling 

Numbers (ADN) and Last Numbers Dialled (LND) 

 Messaging Information, including both Short Message Service (SMS) textual 

messages and Enhanced Messaging Service (EMS) simple multimedia messages. 

 Location Information, including Location Area Information (LAI) for voice 

communications and Routing Area Information (RAI) for data communications 

6.4 Unobstructed Devices 

An unobstructed device refers to a device that does not require a password or other 

authentication technique to be satisfied to gain access to the device and perform an acquisition. 

Anecdotally, most devices seized in investigations appear to fall into this category. 

Unobstructed devices include mainly CDMA phones, freestanding (U)SIMs, and GSM phones 

containing a (U)SIM. A GSM phone that contains no (U)SIM is considered to be an 

“Obstructed Device,” discussed later in this chapter. Depending on the type of the phone, 

potential evidence, particularly user data, may reside in either the volatile or non-volatile 

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Guidelines on Cell Phone Forensics 

memory, and must be handled accordingly. While the recoverable memory of (U)SIMs is 

non-volatile and in and of itself not a concern when found freestanding, their insertion and 

removal from a GSM mobile phone has forensic implications on the contents of the phone that 

must be taken into account. 

To preserve the integrity of the data, examiners should handle the original evidence as little as 

possible. Generally, it is recommended to create a “master” forensic copy of the device case 

file first, which is kept completely pristine. The master copy is then used to create additional 

mirror images needed for analysis and examination of evidence [Gas03]. A strong one-way 

cryptographic hash (e.g., SHA1) should be performed to ensure that the additional images 

created from the master copy are identical. 

6.4.1 Mobile Phone Acquisition 

Often phones are submitted for laboratory processing with only specific items requested for 

recovery, such as phone call logs or images. If any doubt or concerns exist about the requested 

data, contacting the person who initiated the examination for clarification is recommended. 

Though it is not always necessary to recover all available data, a complete acquisition avoids 

having to redo the process later, if other data is needed, and the possibility that technical 

problems may arise on a later attempt. 

To acquire data from a phone, a connection must be established to the device from the forensic 

workstation. Before performing an acquisition, the version of the tool being used should be 

documented, along with any applicable patches or errata from the manufacturer applied to the 

tool. As mentioned earlier, caution should be taken to avoid altering the state of a mobile 

phone when handling it, for example, by pressing keys that could potentially corrupt or erase 

evidence. Once the connection has been established, the forensic software suite can proceed to 

acquire data from the device. Appendix C gives an overview of the steps involved in an 

acquisition. They entail selecting a connection, identifying the device to be acquired, 

identifying the data to be recovered, and viewing the recovered data. 

Acquiring a device’s contents logically, the prevailing technique used by present day forensic 

tools, requires the device to be switched on. This effectively means that the first evidentiary 

principle mentioned in section 4.2 – actions taken should not modify data contained on the 

device – cannot be complied with, strictly speaking. Therefore, the goal during acquisition is 

to affect memory contents as little as possible and then only with the knowledge of what is 

occurring internally, relying more on adherence to the second and third evidentiary principles 

that respectively emphasize high competence of the specialist and the capture of a detailed 

audit trail of the actions taken [ACPO]. 

The date and time maintained on the mobile phone is an important piece of information. The 

date and time may be obtained from the network or manually set by the user. Suspects may 

manually set the day or time to a completely different value from the actual one to leave 

misleading values in the call and message records found on the phone. If the phone was on 

when seized, the date and time maintained and differences from a reference clock should have 

already been recorded, as mentioned earlier. Nevertheless, confirmation at acquisition may 

prove useful. If the phone was off when seized, the date and time maintained and differences 

from a reference clock should be recorded immediately when first turned on in the laboratory. 

Note that actions taken during acquisition, such as removal of the battery to view the device 

label, may affect the time value maintained. 

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Guidelines on Cell Phone Forensics 

Unlike desktop machines or network servers, only a few phones have a hard disk and rely 

instead completely on semiconductor memory. Specialized software exists for performing a 

logical acquisition of PIM data and, for certain phones, producing a physical image. However, 

the contents of a phone are typically dynamic and continually changing. Two back-to-back 

acquisitions of a device using the same tool may produce different results overall (e.g., if 

memory compaction occurs), though the majority of information, such as PIM data, remains 

unchanged. 

Increasingly, mobile phones come with a built-in slot for some family of memory cards. 

Forensic tools that acquire the contents of a resident memory card normally perform a logical 

acquisition. To recover deleted data that might reside on the memory card, a direct acquisition 

can be performed on it after the contents of the mobile phone have been successfully acquired. 

With either type of acquisition, the forensic tool may or may not have the capability to decode 

recovered phone data stored on the card (e.g., SMS text messages), requiring additional 

manual steps to be taken. 

After an acquisition is finished, the forensic specialist should always confirm that the contents 

of a device were captured correctly. On occasion, a tool may fail its task without any error 

notification and require the specialist to reattempt acquisition with the same tool or another 

tool. Similarly, some tools do not work as well with certain devices as others do, and may fail 

with an error notification. Thus, where possible, it is advisable to have multiple tools available 

and be prepared to switch to another if difficulties occur with the initial tool. 

Invariably, not all relevant data viewable on a phone using the available menus can be captured 

through a logical acquisition. For example, draft and archived messages are sometimes not 

recovered by forensic tools. Manually scrutinizing the contents via the phone interface menus 

while video recording the process not only allows such items to be captured and reported, but 

also confirms that the contents reported by the tool are consistent with observable data. 

Manual acquisition must always be done with care, preserving the integrity of the device in 

case further, more elaborate acquisitions need to be conducted. 

The contents of a phone’s memory often contain information, such as deleted data, that is not 

recoverable through either a logical acquisition or a manual examination. Lacking a software 

tool able to perform a physical acquisition, it may be necessary to turn to a hardware-based 

technique. Two techniques commonly used for non-volatile memory are acquisition through a 

standardized Joint Test Action Group (JTAG) test interface, if supported on the device, and 

acquisition by directly reading memory that has been removed from the device [Will05]. The 

techniques are discussed in a bit more detail in section 6.5.3, under Hardware Base Methods. 

6.4.2 GSM Phone Considerations 

CDMA phones and other mobile phones that do not use an identity module are relatively 

straightforward insofar as the acquisition entails a single device. The considerations described 

above are the main considerations to be addressed. GSM phones on the other hand are slightly 

more complex because of the handset/(U)SIM partitioning of the phone. Depending on the 

type of phone, whether it is on or off, and other conditions, the phone and (U)SIM could be 

acquired jointly or separately. 

If the mobile phone is active, a joint acquisition of the handset and (U)SIM contents should be 

carried out before the (U)SIM is acquired directly. A direct acquisition recovers deleted 

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Guidelines on Cell Phone Forensics 

messages present on a (U)SIM, while an indirect acquisition via the handset does not. The 

SIM must be removed from the phone and inserted into an appropriate reader for direct 

acquisition. One reason for this sequence is that removal of the (U)SIM, which is typically 

located beneath the battery, can result in the loss of non-volatile memory due to the power 

disruption. Additionally, the fact that the device was kept in an active state when seized may 

be an indication that some concern exists about triggering authentication or some other 

security mechanism if power is lost. 

A well-known forensic issue that arises when following this sequence is that the reported status 

of unread SMS text messages is inconsistent between each (U)SIM acquisition – the first one 

declaring it to be unread, while the second one read. Reading an unread SMS message from a 

(U)SIM indirectly through the handset causes the operating system of the phone to change the 

status accordingly. Had the (U)SIM been read directly by a tool, no change in status would 

occur. One way to avoid the inconsistency is to omit selecting the recovery of (U)SIMresident SMS text messages when performing the joint acquisition, if the tool allows such an 

option. 

If the mobile phone is inactive, the contents of the (U)SIM may be acquired independently 

before that of the handset. The (U)SIM acquisition should be done directly through a (U)SIM 

reader. The handset acquisition should be attempted without the (U)SIM present. Many 

phones permit an acquisition under such conditions, allowing PIN entry for the (U)SIM to be 

bypassed, if it were enabled. If the acquisition attempt is unsuccessful, the (U)SIM can be 

reinserted and a second attempt made. Performing separate independent acquisitions (i.e., 

acquiring the (U)SIM before acquiring the contents of the handset) avoids any operating 

system-related forensic issues associated with an indirect read of (U)SIM data. However, 

removing the SIM can reportedly cause data to be deleted on some phones [Goo03]. In 

addition, if removing the battery is required to gain access to the SIM, a loss of the date and 

time values can occur in certain phones [Mel04]. Similarly, when the battery is removed from 

certain smart phones, the user data present in volatile memory can be lost if a second backup 

battery is not built-in to support battery replacement or cannot maintain volatile memory for a 

sufficient time. In situations where lost data can occur, the acquisition sequence described at 

the beginning of this section for active phones should be followed. 

6.4.3 (U)SIMs 

Similar to a mobile phone, to acquire data from a (U)SIM, a connection must be established 

from the forensic workstation to the device, using a reader. As before, the version of the tool 

being used should be documented, along with any applicable patches or errata from the 

manufacturer applied to the tool. Once the connection has been established, the forensic 

software tool can proceed to acquire data from the device. 

Capturing a direct image of the (U)SIM data is not possible because of the protection 

mechanisms built into the module. Instead, forensic tools send command directives called 

Application Protocol Data Units (APDUs) to the (U)SIM to extract data logically, without 

modification, from each elementary data file of the file system. The APDU protocol is a 

simple command-response exchange. Each element of the file system defined in the GSM 

standards has a unique numeric identifier assigned, which can be used to walk through the file 

system and recover data by referencing an element and performing some operation, such as 

reading its contents. 

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Guidelines on Cell Phone Forensics 

 

Because (U)SIMs are highly standardized devices, few issues exist with regard to a logical 

acquisition. The main consideration is selecting a tool that reports the status of any PINs and 

recovers the data of interest. Vast differences exist in the data recovered by (U)SIM tools, with 

some recovering only the data thought to have the highest relevance in a typical investigation, 

and others performing a complete recovery of all data, even though much of it is network 

related with little investigative value. 

6.5 Obstructed Devices 

Obstructed devices typically refer to devices that are shut off and require successful 

authentication using a password or some other means to gain access. Common obstructed 

devices include mobile phones with missing identity modules, with PIN-enabled identity 

modules, or with an enabled phone lock setting. Password locked memory cards are beginning 

to emerge as the capability to set such locks appears in more phones. Content encryption 

capabilities are currently not offered as a standard feature in most cell phones, but may be 

available through an add-on application. 

A number of ways exist to recover data from obstructed devices. They fall into three classes: 

investigative, software-based, and hardware-based methods. Experimenting with a seized 

device to bypass or overcome its security mechanisms should be avoided and instead done 

with a test device of the same make, model, and version of software. Seemingly simple 

actions can cause the device to lock permanently or lose data, making evidence recovery more 

difficult or impossible. PIN and password-protected devices may require the expertise of a 

specially trained forensic specialist to gain access to the device contents in a forensically sound 

manner, once conventional techniques have been exhausted. Preserving the contents of the 

device when conventional techniques are applied is vital to allow more sophisticated 

techniques to succeed. 

Software and hardware-based methods are often directed at a particular device or narrow class 

of device, as are some investigative methods. In developing a method, the following actions 

should be considered for determining possible approaches: 

 Contacting the device manufacturer and service provider for information on known 

backdoors and vulnerabilities that might be exploited. 

 Reviewing manufacturer specifications and other documentation when formulating 

plausible approaches. 

 Contacting commercial evidence recovery professionals that specialize in handheld 

devices. 

 Searching Internet sites for developer, hacker, and security exploit information. 

 Contacting device maintenance and repair companies, as well as commercial 

organizations that provide architecture information on handheld device products.26

26 For handheld device architecture information, see http://www.portelligent.com/prodserv.asp. 

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Guidelines on Cell Phone Forensics 

6.5.1 Investigative Methods 

Investigative methods are procedures the investigative team can apply, which require no 

forensic software or hardware tools. The most obvious methods are the following: 

 Ask the suspect – If a device is protected with a password, PIN, token, or other 

authentication mechanism involving knowledge-based authentication, the suspect can 

be queried for this information during the initial interview. 

 Review seized material – Passwords or PINs may be written down on a slip of paper 

and kept with or near the phone, at a desktop computer used to synchronize with the 

phone, or on the suspect’s person, such as within a wallet, and may be recovered 

through visual inspection. Packaging material for a (U)SIM or a GSM phone may 

disclose a PIN unlocking key (PUK) that can be used to reset the value of the PIN. 

 Manually supply commonly used input – Users may weaken a mechanism by the 

way in which it is used. For example, if the (U)SIM of a mobile phone requires a 4-

digit PIN, an examiner may wish to try a commonly used PIN combination (e.g.,1-2-

3-4, 0-0-0-0, etc.), as one of the three attempts allowed before the device is completely 

locked down [Kni02]. Most (U)SIM tools, but not all, report the remaining number of 

attempts. 

 Ask the service provider – If a GSM mobile phone is protected with a PIN-enabled 

(U)SIM, the SIM’s identifier (i.e., the ICCID) can be obtained from it and used to 

request the PUK from the service provider and reset the PIN. Some service providers 

offer the ability to retrieve the PUK on-line, by entering the telephone number of the 

phone and certain subscriber information into public web pages set up for this 

purpose. 

 Exploit possible insecure settings – Some models of phones may easily yield access 

because of common user configuration errors. For example, certain Motorola phones 

provide a two-level access mechanism that can be enabled on the handset: a phone 

lock needed to gain access to the device and a security code needed to reset the phone 

lock in case it is forgotten. A user may set the phone lock, but not change the security 

code from its default value, allowing anyone to gain access using the default security 

code value to reset or disable the phone lock. 

6.5.2 Software-based Methods 

Software-based methods involve software techniques used to break or bypass authentication 

mechanisms. While some general-purpose software techniques and tools may apply to a class 

of mobile phones, most of the techniques are specialized for a specific model within a class. 

When a specialized technique is developed, it is normally programmed and tested on an 

identical test device. Software-based methods include the following: 

 Exploit known weaknesses in authentication – If an authentication mechanism is 

weak, exploiting the weaknesses to defeat it may be possible. For example, early 

password protection schemes on Palm OS PDAs obfuscated the password using a 

reversible algorithm [Kin01], allowing it to be recovered easily from devices running 

version 4.0 or earlier, using a utility. Similarly, early versions of the Pocket PC 

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Guidelines on Cell Phone Forensics 

ActiveSync protocol allow unlimited authentication attempts to be made without 

penalty, allowing a dictionary attack of commonly used passwords to be attempted. 

Some devices may have a reserve password or master password built into the 

authentication mechanism, which allows unfettered access when entered, bypassing 

the phone lock set by the user [Kni02, Smi06]. For example, the master security code 

for overriding the phone lock mechanism on certain Nokia handsets can be calculated 

directly from the equipment identifier.27 A number of GSM mobile phones allow 

acquisition, if a PIN-enabled (U)SIM is missing or removed from the device, as 

mentioned earlier. It is also possible to create a substitute (U)SIM for certain models 

of phones that fools them into treating the (U)SIM as though it were the original and 

allowing access. 

 Gain access through a backdoor – Manufacturers often build in test facilities or 

have other software backdoors that an examiner can exploit to obtain information. 

For example, a few software tools are able to acquire the memory of certain phones 

directly through a diagnostic/debugging protocol that bypasses the authentication 

mechanism. Scanning the memory contents can reveal authentication information 

such as passwords or phone locks. 

The bootloaders on some mobile phones and PDA devices also support functions that, 

among other things, allow the devices’ memory to be read. For instance, the iPAQ 

3900 and other models in that product series support the parrot bootloader, an 

unadvertised utility so named because of the bird that appears on the display [Log01]. 

When triggered by a specific combination key chord and provided appropriate 

commands via the serial port, the bootloader returns the contents of memory or copies 

it to a memory card. Similarly, the penguin bootloader for Linux handheld devices 

can be used to copy memory to a memory card. 

 Exploit known system vulnerabilities – Mobile systems may possess system 

vulnerabilities within a standard interface protocol that an examiner can exploit to 

bypass authentication and gain access to information. For example, access to the 

device may be possible via a misconfigured network service [Cha02], a flaw in a 

standard networking protocol supported by the device, or an error in the protocol’s 

implementation that makes it susceptible to an attack method such as a buffer 

overflow. Possible communications interfaces for exploitation include the serial, 

USB, IrDA, Bluetooth, WiFi, and GSM/GPRS facilities. 

Substitute (U)SIMs: Occasionally, a (U)SIM may not be recovered with a phone, or may be 

intentionally damaged and unusable with the phone, but needed for the acquisition of the phone 

with a forensic tool. One of the most common mistakes a forensic specialist can make is to insert 

another available (U)SIM into the phone to acquire the data with a forensic tool. Certain data 

stored in the memory of the phone, such as call logs (missed, incoming and outgoing calls) and 

SMS messages, is linked to the last (U)SIM used. Inserting a different (U)SIM causes that data to 

be erased from the phone’s memory. Some phones may also start copying SIM data to the 

phone memory when another (U)SIM is inserted. 

 

27 For more information, see http://www.fonefunshop.co.uk/Unlocking/nokiasecuritycode.htm. 

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Guidelines on Cell Phone Forensics 

A better approach is to create a substitute (U)SIM to use with the phone that mimics key 

characteristics of the original (U)SIM, tricking the phone to accept it as the original. Several tools 

that can be used to create a substitute (U)SIMs are the Forensic SIM Toolkit, GSM .XRY SIM ID 

Cloner, SIMgen, and the TULP 2G SIMIC protocol plug-in. 

Substitute (U)SIMs, sometimes referred to as access cards, can be useful in a number of 

situations: 

• As already mentioned, if the (U)SIM for a phone is missing or damaged and needed for 

acquisition with a forensic tool, a substitute (U)SIM allows phone data to be recovered. 

• If the (U)SIM for a phone is present, but requires a PUK code, a substitute (U)SIM allows 

acquisition to proceed immediately without having to contact the service provider for the PUK. 

• If radio isolation is needed to prohibit communications to acquire evidence from a phone, 

avoiding incoming calls or messages from altering or modifying evidence, a substitute (U)SIM can 

be used in lieu of a Faraday room or enclosure. 

• If the forensic tool used to examine a handset accesses the resident (U)SIM indirectly, using 

a substitute (U)SIM in the handset eliminates the possibility of the original being altered during 

examination. 

The values by which the phone remembers the previously inserted (U)SIMs are the ICCID and 

the IMSI. Often only one of these values is used. Both identifiers are unique and used to 

authenticate the user to the network. If these values are known for a specific phone (e.g., either 

indirectly through the service provider records or directly by reading memory from the phone), it 

may be possible to prepare a substitute (U)SIM with the correct values needed to trick the phone 

to accepting it. While the minimum data needed to create a (U)SIM may be simply one of these 

two values, some phones may require additional data to be populated on the (U)SIM to be 

correctly recognized. The possibility exists that data, other than user data, may change on the 

handset as the result of inserting a substitute (U)SIM [INT06]. 

6.5.3 Hardware-based Methods 

Hardware-based methods involve a combination of software and hardware to break or bypass 

authentication mechanisms and gain access to the device. For example, the value of a phone 

lock can be readily recovered from a memory dump of certain phones, allowing for a followon logical acquisition. Few general-purpose hardware-based methods apply to a general class 

of mobile phone. Most of the techniques are specialized for a specific model within a class. 

As with software-based methods, when a specialized technique is developed, a test device 

identical to the one under examination should be used. The device manufacturer may also 

provide useful information and tools for extracting data. Hardware-based methods include the 

following: 

 Gain access through a hardware backdoor – Hardware backdoors, such as 

interfaces for debugging, production testing, or maintenance, may be used to gain 

access to memory. For example, some mobile phones have active hardware test 

points on the circuit board that can be used to probe the device. Many manufacturers 

now support the JTAG standard, which defines a common test interface for processor, 

memory, and other semiconductor chips, on their devices [Int96]. Forensic examiners 

can communicate with a JTAG-compliant component by utilizing software and an 

add-in hardware controller in a personal computer card slot or a special purpose 

51
Guidelines on Cell Phone Forensics 

 

standalone programmer device to probe defined test points [Will05]. The JTAG 

testing unit can send commands and data to the JTAG-compliant component and 

return the results to the unit for storage and rendition [Bre06, Xjt03]. JTAG gives 

specialists another avenue for imaging devices that are locked or devices that may 

have minor damage and cannot be properly interfaced otherwise. 

 Examine memory independently of the device – An experienced examiner may be 

able to examine memory chips directly on the device and extract information from 

them. For example, the Netherlands Forensic Institute has developed a generalpurpose tool for examining a wide range of memory chips. Once physically 

connected via a memory clip, the tool is able not only to read and store memory 

contents, but also to overwrite them [Kni02]. Memory may also be acquired by 

dismantling the phone, heating the circuit board sufficiently to desolder the memory 

chips, and using a memory chip reader to access their contents [Will05]. 

 Find and exploit vulnerabilities – Mobile phone vulnerabilities discovered through 

close study and experimentation are sometimes posted on the Web.28 They can also 

be discovered through reverse engineering. Reverse engineering involves retrieving 

the operating system code from the ROM of a mobile phone identical to the one under 

examination and analyzing the code to understand its structure and use of the device 

hardware [Haa04]. With the understanding gained, any plausible vulnerabilities noted 

can be systematically tested to determine a useful exploit technique. For example, for 

a password authentication mechanism, it may be possible using memory injection to 

overwrite the password with a known value or replace the authentication program 

with a version that always authenticates successfully [Kni02]. Similarly, flipping two 

bits in a data structure, which determine whether the start-up password is active and 

configured, may turn off the mechanism completely, as reported for the XDA 

PDA/phone hybrid device [Its]. 

 Infer information by monitoring physical device characteristics – Techniques that 

monitor power consumption or other device characteristics have been effective in 

systematically determining the password or PIN. For example, forensic specialists 

report that the passwords of some electronic organizers have been uncovered by 

determining the address area of the password and, as characters are entered, 

systematically monitoring the data and address bus of those memory locations to 

reveal the value one character at a time [Kni02]. Differential power analysis, which 

has been shown to be effective in gaining information from smart cards, is another 

technique that could be applied [Aig]. Simply observing data on an interface can also 

reveal information. For example, the dialog between the phone and a passwordprotected memory card can be monitored to reveal the password supplied by the 

phone to unlock the card, which can then be used in an external examination to access 

the memory card contents. 

 Use automated brute force – If a password mechanism has no restrictions on the 

number of manual attempts made and the examiner had time to spare, a brute force 

dictionary attack could be attempted. Normally, this approach would be out of the 

28 For example, a security hole discovered in the Motorola MPx200 is discussed at 

http://msmobiles.com/news.php/1640.html. 

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Guidelines on Cell Phone Forensics 

question. However, with automated keystroke entry, it is plausible. For example, the 

Netherlands Forensic Institute developed an automated password entry system for 

devices with a keyboard and screen. Equipped with a robot arm and video camera, 

the unit can systematically enter passwords until the correct entry is detected or, in the 

worst case, the keys become damaged [Kni02]. 

6.6 Tangential Equipment 

Tangential equipment includes devices that contain memory and are associated with a mobile 

phone. The two main categories are memory cards and host computers to which a mobile 

phone has synchronized its contents. Surprisingly, USB memory drives, which are a common 

peripheral for host computers, are generally not a factor for mobile phones because of interface 

issues. 

Mobile phones, especially higher smart phones, typically support Secure Digital (SD), 

MultiMedia Cards (MMC), and other types of removable media designed specifically for 

handheld devices, which can contain significant amounts of data. Memory cards are typically 

semiconductor memory, used as auxiliary user file storage, for backup of important content, or 

as a means to convey files to and from the device. The physical sizes of memory cards 

supported by handheld devices are noteworthy insofar as they are quite small, about the size of 

a coin, and easy to overlook. Therefore, investigators should take their time and thoroughly 

search the premises when seizing material. Data can be acquired from removable media with 

the use of a media reader and a forensic application used to image hard drives. 

The data contained on a mobile phone is often present on a personal computer, due to the 

capability of mobile phones to synchronize or otherwise share information among one or more 

host computers. Such personal computers or workstations are referred to as synched devices. 

Because of synchronization, a significant amount of evidence on a mobile phone may also be 

present on the suspect’s laptop or personal computer, and recovered using a conventional 

computer forensic tool for hard drive acquisition and examination. 

6.6.1 Synched Devices 

Synchronization refers to the process of resolving differences in certain classes of data, such as 

e-mail residing on two devices (i.e., a mobile phone and a computer), to obtain a version that 

reflects any actions taken by the user (e.g., deletions or additions) on one device or the other. 

Synchronization of information may occur at either the record level or the file level. When 

done at the file level, any discrepancies from the last synchronization date and time result in 

the latest version automatically replacing the older version. Occasionally manual intervention 

may be needed if both versions were modified independently since the last synchronization 

occurred. Record level synchronization is done similarly, but with more granularity, whereby 

only out-of-date parts of a file are resolved and replaced. 

Phones are typically populated with data from the personal computer during the 

synchronization process. A significant amount of informative data, therefore, may reside 

locally on a personal computer. Data from the phone can also be synchronized to the 

computer, through user-defined preferences in the synchronization software. Because the 

synchronized contents of a phone and personal computer tend to diverge quickly over time, 

additional information may be found in one device or the other. 

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Guidelines on Cell Phone Forensics 

The synchronization software and the device type determine where the phone’s files are stored 

on the PC. Each synchronization protocol has a default installation directory, but the locale 

can be user specified. 

6.6.2 Memory Cards 

Mobile phones use a wide array of memory cards, ranging from the size of a contact lens to 

that of a matchbook. Unlike RAM within a device, such removable media is non-volatile 

storage and requires no battery to retain data. Memory card storage capacity ranges from 8MB 

to 2GB and beyond. As technological advances are made, such media becomes smaller and 

offers larger storage densities. Removable media extends the storage capacity of mobile 

phones, allowing individuals to store additional files beyond the device’s built-in capacity and 

to share data between compatible devices. 

Some forensics tools are able to acquire the contents of memory cards; many are not. If the 

acquisition is logical, deleted data present on the card is not recovered. Fortunately, such 

media can be treated similarly to a removable disk drive, and imaged and analyzed using 

conventional forensic tools with the use of an external media reader. Memory card adapters 

exist that support an Integrated Drive Electronics (IDE) interface. Such adapters allow 

removable media to be treated as a hard disk and used with a write blocker, which ensures that 

the removable media remains unaltered. A Universal Serial Bus (USB) memory card reader 

used with write blocker hardware is also an available alternative. 

Data contained on the media can be imaged and searched, and deleted files can be recovered, 

providing possibilities of uncovering evidence. One drawback is that phone data, such as SMS 

text messages, stored on the media may require manual decoding or a separate decoding tool to 

interpret. A more serious issue is that content protection features incorporated into the card 

may block the recovery of data. The most notable example is MMC cards that conform to 

version 4.1 of the standard, which provides for password protection and is supported 

increasingly on newer models of phones. Table 5 gives a brief overview of various storage 

media in use today. 

Table 5: Memory Cards 

Name Characteristics 

Compact Flash Card (CF) Matchbook size (length-36.4 mm, width-42.8 mm, thickness-3.3 mm for 

Type I cards and 5mm for Type II cards) 

50-pin connector, 16-bit data bus 

MMCplus (compatible 

with original MultiMedia 

Card or MMC) 

Postage stamp size (length-32 mm, width-24 mm, and thickness-1.4 

mm) 

13-pin connector, 1, 4, or 8 bit data bus 

(7-pin connector, 1-bit data bus, MCC compatibility) 

MMCmobile (compatible 

with original Reduced Size 

MMC or RS-MMC) 

Thumbnail size (length-18 mm, width-24 mm, and thickness-1.4 mm) 

13-pin connector, 1, 4, or 8 bit data bus 

(7-pin connector, 1-bit data bus, RS-MMC compatibility) 

Requires a mechanical adapter to be used in a full size MMCplus slot 

MMCmicro Contact lens size (length-14 mm, width-12 mm, and thickness-1.1 mm) 

10-pin connector and a 1 or 4-bit data bus 

Requires a mechanical adapter to be used in a full size MMCplus slot 

Secure Digital (SD) Card Postage stamp size (length-32 mm, width-24 mm, and thickness-2.1mm) 

9-pin connector, 1 or 4-bit data bus 

Features a mechanical erasure-prevention switch 

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Guidelines on Cell Phone Forensics 

Name Characteristics 

MiniSD Card Thumbnail size (length-21.5 mm, width-20 mm, and thickness-1.4 mm) 

9-pin connector, 1 or 4-bit data bus 

Requires a mechanical adapter to be used in a full size SD slot 

MicroSD (formerly 

Transflash) 

Contact lens size (length-15 mm, width-11 mm, and thickness-1 mm) 

6-pin connector, 1 or 4-bit data bus 

Requires a mechanical adapter to be used in a full size SD slot 

Memory Stick Chewing gum stick size (length-50 mm, width-21.45 mm, thickness-2.8 

mm) 

10-pin connector, 1-bit data bus 

Features a mechanical erasure-prevention switch 

Memory Stick Duo Partial chewing gum stick size (length-31mm, width-20 mm, thickness1.6 mm) 

10-pin connector, 4-bit data bus 

Features a mechanical erasure-prevention switch 

Requires a mechanical adapter to be used in a full size Memory Stick 

slot

Memory Stick Micro Contact lens size (length-12.5 mm, width-15 mm, and thickness-1.2 mm) 

11-pin connector, 4-bit data bus 

Requires a mechanical adapter to be used in a full size Memory Stick 

slot

Memory cards may support extensions for added functionality. For example, the X-Mobile 

Card from Renesas is a MultiMedia card that contains both a smart card and a memory chip. 

Through the use of a built-in controller, the card is able to function in either mode. Another 

example is SD cards that have WiFi or other wireless capability. 

6.6.3 USB Memory Drives 

USB drives, sometimes referred to as thumb drives, are chewing-gum-pack size hardware 

components with a USB connector at one end, and built as a printed circuit board within a 

plastic housing that encases a processor and memory. USB memory drives can be treated 

similarly to a removable disk drive, and imaged and analyzed using conventional forensic 

tools. 

Many manufacturers produce USB memory drives of various capacities. Currently, however, 

very few mobile phones support host USB ports, which are needed to interface with these 

peripherals. Moreover, few if any USB drive manufacturers provide the necessary drivers for 

mobile phone operating systems. This situation is understandable, given that host USB 

specifications intend for an interface to be capable of supporting multiple devices sharing the 

port, which if permitted would place a significant power drain on the battery of the device. 

Other factors include the restrictions in mobility imposed by a USB drive sticking out of the 

side of a mobile phone compared to the benefits of providing one or more memory card slots 

that completely contain a card when inserted. 

As with memory card extensions, USB drives may offer additional capabilities such as a 

wireless interface. Access to memory contents may also be protected through a built-in 

fingerprint reader or some other mechanism such as a smart card, which complicates the 

acquisition process. However, for the reasons mentioned above these peripherals are not 

normally associated with mobile phones. 

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Guidelines on Cell Phone Forensics 

7. Examination and Analysis 

The examination process uncovers digital evidence, including that which may be hidden or 

obscured. The results are gained through applying established scientifically based methods, 

and should describe the content and state of the data fully, including the source and the 

potential significance. Data reduction, separating relevant from irrelevant information, occurs 

once the data is exposed. The analysis process differs from examination in that it looks at the 

results of the examination for its direct significance and probative value to the case [ACPO]. 

Examination is a technical process that is the province of a forensic specialist. However, 

analysis may be done by roles other than the forensic analyst, such as the investigator or the 

forensic examiner. 

The examination process begins with a copy of the evidence acquired from the device. 

Fortunately, compared with classical examination of individual workstations or network 

servers, the amount of acquired data to examine is much smaller with mobile phones. Because 

of the prevalence of proprietary case file formats, the forensic toolkit used for acquisition will 

typically be the one used for examination and analysis. Interoperability among the acquisition 

and examination facilities of different tools is also unlikely for this reason, with the exception 

of certain Palm OS devices and perhaps other devices with a PDA lineage. 

The examiner should have studied the case, if possible, and become familiar with the 

parameters of the wrongdoing, the parties involved, and potential evidence that might be 

found. Conducting the examination in a partnership with the forensic analyst or the 

investigator guiding the case construction is advisable for the examiner. The investigator or 

analyst provides insight into the types of things sought, while the forensic examiner provides 

the means to find relevant information that might be on the system [Wol03]. 

If the forensic examiner performs the analysis independently, without conferring directly with 

the forensic analyst or investigator, the understanding gained by studying the case should 

provide ideas about the type of data to target and specific keywords or phrases to use when 

searching the acquired data. Depending on the type of case, the strategy varies. For example, 

a case about child pornography may begin with browsing all of the graphic images on the 

system, while a case about an Internet-related offense might begin with browsing the Internet 

history files [Wol03]. 

Examination often reveals not only potentially incriminating data but also useful information 

such as passwords, network logon names, and Internet activity. Certain data can also provide 

linkage to other potential sources of evidence maintained elsewhere, particularly by network 

service providers. In addition to evidence directly related to an incident, information can be 

uncovered about the lifestyle of suspects, their associates, and the types of activities in which 

they are involved. 

7.1 Potential Evidence 

Mobile phone manufacturers typically offer a similar set of information handling features and 

capabilities, including Personal Information Management (PIM) applications, messaging and 

e-mail, and Web browsing. The set of features and capabilities can vary, of course, with the 

era in which the phone was manufactured, the version of firmware running, modifications 

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Guidelines on Cell Phone Forensics 

made for a particular service provider, and any modifications or applications installed by the 

user. The potential evidence on these devices includes the following items: 

 Subscriber and equipment 

identifiers 

 Date/time, language, and 

other settings 

 Phonebook information 

 Appointment calendar 

information 

 Text messages 

 Dialed, incoming, and missed 

call logs 

 Electronic mail 

 Photos 

 Audio and video recordings 

 Multi-media messages 

 Instant messaging and Web 

browsing activities 

 Electronic documents 

 Location information 

Other data found on a mobile phone may also prove useful in an investigation. For example, 

something seemingly immaterial such as ring tones can have relevance, given that mobile 

phone users often load distinctive ring tones onto a phone to distinguish theirs from others’. A 

witness to an incident may recall having heard a particular tune on a suspect’s phone, which 

may contribute to the identification of an individual. Even esoteric network information found 

on a (U)SIM may prove useful in an investigation. For example, if a network rejects a location 

update from a phone attempting to register itself, the list of forbidden network entries in the 

Forbidden PLMNs elementary file is updated with the code of the country and network 

involved [3GP05a]. The phone of an individual suspected of traveling to a neighboring 

country might be checked for this information. 

The items present on a device are dependent not only on the features and capabilities of the 

phone, but also on the voice and data services subscribed to by the user. For example, prepaid 

phone service typically does not include data services and rules out the possibility for multimedia messaging, electronic mail, and Web browsing. Similarly, a contract subscription may 

selectively exclude certain types of service, though the phone itself could support them. 

Reported Examples: News articles sometimes describe the types of digital evidence found on a 

mobile phone that was used successfully in an investigation. Some illustrative examples are 

given below. 

 Text Message and Call Data – “A pastor of the Pentecostal congregation in the small 

community of Knutby was sentenced to life in prison for persuading one of his lovers (the au 

pair) to shoot and kill his wife and trying to kill the husband of another mistress. Two days 

after the murder, the pastor’s au pair Sarah S. claimed that she did it. Despite her claims ... 

the police believed she had an accomplice.” 

“The strongest evidence against the pastor was the extensive communication through text 

messages and voice calls between him and the au pair on the day of the murder and just 

before that. What they did not know was that their (anonymously sent and) carefully deleted 

text messages were possible to recover.” [Bur05] 

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Guidelines on Cell Phone Forensics 

 Email Data – “The case against Dan Kincaid was strong. A homeowner in northern Boise, 

Idaho, had identified Mr. Kincaid, 44, as the person who had broken into his suburban house. 

But eyewitness testimony isn't always rock solid, and Mr. Kincaid was refusing to talk. The 

police wanted more. So they searched Mr. Kincaid's BlackBerry e-mail-capable phone 

electronically, and found all the evidence they needed.“ 

“‘Just trying to find a way out of this neighborhood without getting caught,’ Mr. Kincaid wrote 

to his girlfriend on Aug. 1, 2005, shortly after he had been spotted. ‘Dogs bark if I'm between 

or behind houses. ... ‘ ‘Cops know I have a blue shirt on,’ he continued. ‘I need to get out of 

here before they find me.’ Faced with his e-mailed admission, Mr. Kincaid agreed to a deal 

with prosecutors over that crime and a string of others.” [Sha06]

 Image and Multi-media Message Data – “It was alleged that a young boy had conducted a 

serious assault on another child whilst his friend took pictures on his mobile phone. The 

young boy was initially denying all knowledge of the incident, until the Police were informed 

that there was evidence on the mobile phone.” “... analysts recovered the pictures in 

question in a forensically sound manner following ACPO guidelines. They also recovered a 

deleted multimedia text message sent to another child with one of the pictures attached to 

it.”29

 Location Data – “Mr Bristowe told BBC News Online: ‘It was mobile phone evidence which 

made the police look more closely at Huntley. He had been Mr. Useful, helping them to 

search the college grounds, but when they checked Jessica's phone and discovered when 

and where it had been switched off alarm bells began to ring... (Jessica's phone) 

disengaged itself from the network, in effect it says goodbye’ at 1846 BST on the Sunday 

when the girls disappeared. Jessica's phone contacted the Burwell mast when it was turned 

off.” 

"’The police provided us with a map of the route they thought the girls would have taken, and 

the only place on that route where the phone could have logged on to Burwell (and 

disengaged itself) was inside or just outside Huntley's house.’ It is believed to be that crumb 

of crucial evidence which forced Huntley to change his story earlier this year and suddenly 

admit the girls died in his bathroom.” [Sum03]

Two types of computer forensic investigations generally take place. The first type is where an 

incident has occurred, but the identity of the offender is unknown (e.g., a hacking incident). 

The second is where the offender and the incident are both known (e.g., a child-porn 

investigation). Prepared with the background of the incident, the forensic examiner and 

analyst can proceed toward accomplishing the following objectives: 

 Gather information about the individual(s) involved {who}. 

 Determine the exact nature of the events that occurred {what}. 

 Construct a timeline of events {when}. 

 Uncover information that explains the motivation for the offense {why}. 

 

29 For more information, see “Mobile Phone Analysis – video retrieval” Case Study at http://www.cclforensics.com/Case_Studies-27.html?linkto=38. 

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 Discover what tools or exploits were used {how}. 

Table 6 below provides a cross reference of generic evidence sources commonly found on 

mobile phones and their likely contribution toward satisfying the above objectives. In many 

instances, the data is peripheral to an investigation, useful in substantiating or refuting the 

claims of an individual about some incident. On occasion, direct knowledge, motivation, and 

intention may be established. Most of the evidence sources are from PIM data, call data, 

messaging, and Internet related information. Other support applications that run on the device 

potentially provide other evidence sources. User files placed on the device for rendition, 

viewing, or editing are also another important evidence source. Besides graphic files, other 

relevant file content includes audio and video recordings, spreadsheets, presentation slides, and 

other similar electronic documents. Installed executable programs may also have relevance in 

certain situations. Perhaps the most important data recovered is that which links to information 

held by the service provider. Service providers maintain databases for billing or debiting 

accounts based on call logs, which can be queried using the subscriber or equipment 

identifiers. Similarly, undelivered SMS text messages, multi-media, or voice messages may 

also be recoverable. 

Table 6: Cross Reference of Sources and Objectives 

Who What Where When Why How 

Subscriber/Device 

Identifiers 

X

Call Logs X X 

Phonebook X

Calendar X X X X X X 

Messages X X X X X X 

Location X X 

Web URLs/Content X X X X X X 

Images/Video X X X X X 

Other File Content X X X X X X 

7.2 Applying Tools 

Once a copy of the acquisition results is available, the next steps involve searching the data, 

identifying evidence, creating bookmarks, and developing the contents of a final report. 

Knowledge and experience with the tools used for examination is extremely valuable, since 

proficient use of the available features and capabilities of a forensic tool can greatly speed the 

examination process. 

Forensic tools are a crucial component, as they translate data from a raw encoded form to a 

format and structure that is understandable by the examiner, enabling identification and 

recovery of evidence. A variety of different and sometimes unusual encodings are used with 

59
Guidelines on Cell Phone Forensics 

cell phone data and found in the memory of handsets and (U)SIMS, such as text encoded in 

the packed 7-bit GSM alphabet, which would be onerous, errorful, and time consuming to 

decode manually. 

It is important to note that forensic tools have the possibility to contain some degree of error in 

their operation. For example, the implementation of the tool may have a programming error; 

the specification of a file structure used by the tool to translate bits into data comprehensible by 

the examiner may be inaccurate or out of date; or the file structure generated by another 

program as input may be incorrect, causing the tool to function improperly [Car02]. 

Experiments conducted with mobile phone forensic tools indicate a prevalence of such errors 

[Aye05, Jan06, Aye07]. Therefore, having a high degree of trust and understanding of the 

tool’s ability to perform its function properly is essential. 

A knowledgeable suspect may tamper with device information, such as purposefully 

misnaming a file extension to foil the workings of a tool, altering the date/time of the phone to 

falsify timestamps associated with logged activities, creating false transactions in the memory 

of the phone or (U)SIM, or applying a wiping tool to remove or eliminate data from memory. 

Seasoned experience with a tool provides an understanding of its limitations, allowing an 

examiner to compensate for them and avoid error to achieve the best possible results. 

To uncover evidence, specialists should gain a background of the suspect and offense and 

determine a set of terms for the examination. Search expressions can be developed in a 

systematic fashion, such as using contact names that may be relevant. By proceeding 

systematically, the specialist creates a profile for potential leads that may unveil valuable 

findings. Forensic Examination of Digital Evidence – A Guide for Law Enforcement, 

produced by the U.S. Department of Justice [DOJ04], offers the following suggestions for the 

analysis of extracted data: 

 Ownership and possession – Identify the individuals who created, modified, or 

accessed a file, and the ownership and possession of questioned data by placing the 

subject with the device at a particular time and date, locating files of interest in nondefault locations, recovering passwords that indicate possession or ownership, and 

identifying contents of files that are specific to a user. 

 Application and file analysis – Identify information relevant to the investigation by 

examining file content, correlating files to installed applications, identifying 

relationships between files (e.g., e-mail files to e-mail attachments), determining the 

significance of unknown file types, examining system configuration settings, and 

examining file metadata (e.g., documents containing authorship identification). 

 Timeframe analysis – Determine when events occurred on the system to associate 

usage with an individual by reviewing any logs present and the date/time stamps in 

the file system, such as the last modified time. Besides call logs, the date/time and 

content of messages and e-mail can prove useful. Such data can also be corroborated 

with billing and subscriber records kept by the service provider [Hos98]. 

 Data hiding analysis – Detect and recover hidden data that may indicate knowledge, 

ownership, or intent by correlating file headers to file extensions to show intentional 

obfuscation; gaining access to password-protected, encrypted, and compressed files; 

60
Guidelines on Cell Phone Forensics 

gaining access to steganographic information detected in images; and gaining access 

to reserved areas of data storage outside the normal file system. 

The capabilities of the tool and the richness of its features, versus the operating system and 

type of device under examination, determines what information can be recovered, identified, 

and reported, and the amount of effort needed. The search engine plays a significant role in the 

discovery of information used for the creation of bookmarks and final reporting. For example, 

some tools used to search for textual evidence identify and categorize files based on file 

extension, where others use a file signature database. The latter feature is preferable since it 

eliminates the possibility of missing data because of an inconsistent file name extension (e.g., 

eliminating a text file whose extension was changed to that of a graphics or image file). 

Similarly, the ability for the tool to find and gather images automatically into a common 

graphics library for examination is extremely useful. 

Searching data for positive results on incriminating evidence takes patience and can be time 

consuming. Some tools have a simple search engine that matches an input text string exactly, 

allowing only for elementary searches to be performed. Other tools incorporate more 

intelligent and feature rich search engines, allowing for generalized regular expression patterns 

(grep) type searches, including wildcard matches; filtering of files by extension, directory, etc.; 

and batch scripts that search for specific types of content (i.e., e-mail addresses, URLs). The 

greater the tool’s capabilities, the more the forensic examiner benefits from experience with 

and knowledge of the tool. 

7.3 Call and Subscriber Records 

Records maintained by the service provider capture information needed to accurately bill a 

subscriber or, in the case of a prepaid service plan, debit the balance. The records collected are 

referred to as call detail records, which are generated by the switch handling an originating call 

or SMS message from a mobile phone. For some service providers, the records may also 

include fixed line, international gateway, and voice over IP transaction information. While the 

content and format of these records can differ widely from one service provider to another, the 

fundamental data needed to identify the subscriber/device initiating the call, the initial cell 

servicing the call, the number dialed, and the duration of the call is captured. Detailed 

information such as the identifier of the cell (i.e., the BTS) and the sector involved are often 

included. Appendix D gives an example of the data elements of a call detail record, specified 

in the GSM standards. As one can see, considerable discretion about what is implemented is 

left open to the service providers and network operators. 

The retention period for maintaining call detail and other types of records varies among service 

providers [GSM05]. However, the period is generally limited, requiring immediate action to 

avoid data loss. One should act quickly to have the cellular carrier preserve any data that can 

be used to identify communications that have occurred and are linked to the parties of interest, 

stressing non-disclosure of that action to the account subscriber [Ala03, Ala04]. The data 

available may include subscriber records, the content of email servers (i.e., undelivered email), 

email server logs, RADIUS or other IP address authentication logs, the content of SMS and 

MMS message servers, and the content of voicemail servers. Note that certain types of 

undelivered content, such as voicemail, may be considered in transit from a legal standpoint in 

some jurisdictions, and obtaining or listening to them without the proper authority may be 

treated as an illegal interception of communications [Ala03]. While the USA PATRIOT Act 

61
Guidelines on Cell Phone Forensics 

 

eliminated this issue at the federal level, state statutes may be intentionally more restrictive or 

not yet be realigned completely with the federal statute.30

Call detail records can be obtained from U.S. service providers through their law enforcement 

point of contact, with the appropriate legal documents. Procedures may vary among states in 

the U.S., and new laws regarding proper seizure are continually legislated. Procedures also 

vary for getting records from service providers and network operators located in other 

countries. Close and continuing consultation with legal counsel is advised. Various on-line 

law enforcement forums can also be helpful in identifying points of contact and sharing tips on 

procedures for accurately obtaining the required data.31

Besides call detail records, subscriber records maintained by a service provider can provide 

data useful in an investigation. For example, for GSM systems, the database usually contains 

the following information about each customer [Wil03]: 

 Customer name and address 

 Billing name and address (if other than customer) 

 User name and address (if other than customer) 

 Billing account details 

 Telephone number (MSISDN) 

 IMSI 

 (U)SIM serial number (ICCID) 

 PIN/PUK for the (U)SIM 

 Services allowed 

Other useful information, including phone numbers (i.e., work or home), contact information 

(e.g., email address), and credit card numbers used, may also be retained in subscriber records. 

Pay-as-you-go prepaid phones purchased anonymously over the counter may also have useful 

information maintained with their accounts, which was supplied by the subscribers, such as the 

credit card numbers used for purchases of additional time or an email address registered online 

for receipt of notifications. Gaining access to the call records of prepaid phones should not be 

ruled out. 

Call detail records and other records maintained by the service provider can be requested using 

subscriber or equipment identifier information seized or acquired from a phone or (U)SIM. 

Subscriber information often used for this purpose includes the IMSI from the (U)SIM and the 

cell phone number. Equipment identifiers used are the ESN or IMEI of the phone and the 

30 For example, see the California wiretap clarification bill at http://info.sen.ca.gov/pub/bill/asm/ab_1301-

1350/ab_1305_cfa_20050603_115538_sen_comm.html. 

31 For example, see the PhoneForensics Yahoo Group at http://groups.yahoo.com/group/phoneforensics/ or the High 

Tech Crime Consortium mail list at https://htcc.secport.com/mailman/listinfo/htcc. 

62
Guidelines on Cell Phone Forensics 

 

serial number (i.e., ICCID) of the (U)SIM. The search criteria used could be, for example, all 

calls received by a certain phone number (e.g., that of a victim) or all calls handled by a base 

station responsible for a particular cell (i.e., to determine who was in a certain area at a certain 

time) [Wil05]. The analysis of the initial set of records obtained usually leads to additional 

requests for related records of other subscribers and equipment, based on the data uncovered. 

For example, frequent calls to a victim’s mobile phone from one or more other phones before a 

homicide would logically lead to interest in obtaining the records of the caller(s). 

Call detail records can be analyzed for a variety of purposes. For example, a service provider 

may use them to understand the calling patterns of their subscribers and the performance of the 

network [Aja06, Hin96]. Call detail records can also be used with cell site tower information 

obtained from the service provider to translate cell identifiers into geographical locations for 

the cells involved and identify the general locale from which calls were placed. While plotting 

call record locations and information onto a map can sometimes be useful, it does not 

necessarily provide a complete and accurate picture. Cell towers can service phones at 

distances of up to 35 kilometers (approximately 21 miles) and may service several distinct 

sectors. Radio frequency coverage maps maintained by the service provider can be obtained to 

create a more exact portrayal of the data for the sectors involved. The results of the data 

analysis can be used to corroborate or refute statements made by individuals regarding their 

whereabouts at a given time. A change of cell identifier between the beginning and the end of 

a call, over a series of calls, may also indicate a general direction of travel or pattern of 

behavior. 

Cell boundaries are somewhat fuzzy. Various factors, such as terrain, seasonal changes, 

antenna performance, and call loading, affect the coverage area of cells and the plausible locale 

to associate with a call record. Detailed field tests and measurements may be required to ensure 

accuracy the analysis. Such surveys are regularly performed by network operators to verify 

and improve network performance [Ko96]. Tools also exist to aid law enforcement in 

performing cell site analysis and mapping activities independently.32 In some situations, 

however, such as densely populated urban locations involving microcells or picocells with a 

limited coverage area, location determination may be relatively straightforward by the very 

nature of the network [Gar01]. 

Identifying the geographical coverage of specific cells can provide valuable information when 

combined with call detail records, geographically establishing plausible locations with some 

degree of certainty for the times involved. Professional criminals are aware of these 

capabilities and may attempt to turn them to their advantage by having someone use their 

phone to establish a false alibi. Attempts at evasion may also occur. A common ploy used is 

to purchase, use, and quickly dispose of pay-as-you-go prepaid phones to minimize exposure 

or use stolen phones. To obfuscate usage and complicate analysis of records, a variety of 

different (U)SIMs may be swapped among different GSM/UMTS handsets. 

Careful analysis of the call records in conjunction with other forms of available evidence 

overcomes most of these kinds of attempts at evasion. For example, call detail records of payas-you-go prepaid phones are maintained by and available from network providers, the same 

as for contract subscriptions. By analyzing the patterns and content of communications and 

32 For example, see the Cell View information at http://www.icardforensics.com/documents/CellSiteMonitor.pdf or 

the CSurv information at http://www.teeltech.com/tt/TeelTechCsurv.pdf.pdf. 

63
Guidelines on Cell Phone Forensics 

mapping the evidence to known associates of a suspect, ownership of such phones is possible 

to establish. Other traditional forms of forensic evidence may also be used to establish 

ownership. 

64
Guidelines on Cell Phone Forensics 

8. Reporting 

Reporting is the process of preparing a detailed summary of all the steps taken and conclusions 

reached in the investigation of a case. Reporting depends on maintaining a careful record of all 

actions and observations, describing the results of tests and examinations, and explaining the 

inferences drawn from the evidence. A good report relies on solid documentation, notes, 

photographs, and tool-generated content. 

Reporting occurs once the data has been thoroughly searched and relevant items bookmarked. 

Many forensic tools come with a built-in reporting facility that usually follows predefined 

templates and may allow customization of the report structure. Permitted customizations 

include allowing for organization logos and report headers and selection of styles and structure 

to provide a more professional look tailored to the organization’s needs. Reports generated by 

a forensic tool typically include items from the case file, such as the specialist’s name, a case 

number, a date and title, the categories of evidence, and the relevant evidence found. Report 

generation typically either outputs all of the data obtained or allows examiners to select 

relevant data (i.e., bookmarked items) for the final report. Including only relevant findings in 

the report minimizes its size and lessens confusion for the reader. 

The software-generated contents are only one part of the overall report. The final report 

contains the software-generated contents along with data accumulated throughout the 

investigation that summarizes the actions taken, the analysis done, and the relevance of the 

evidence uncovered. Ideally, the supporting documentation is in electronic form and able to be 

incorporated directly into the report. 

Reporting facilities vary significantly across mobile device acquisition applications. Report 

generation typically can render a complete report in one of several common formats (e.g., .txt, 

.rtf, .csv, .doc, .html) or at least provide a means to export out individual data items to compose 

a report manually. A few tools include no means of report generation or data export and 

instead require examiners to capture individual screenshots of the tool interface for later 

assembly into a report format. Regardless of how reports are generated, checking that the 

finalized report is consistent with the data presented in the user interface representation is vital 

to identify and eliminate any possible inconsistencies that may appear [Aye05, Jan06, Aye07]. 

The ability to modify a pre-existing report and incorporate data (e.g., images, video stills) 

captured by alternative means is advantageous. Auxiliary acquisition techniques are sometime 

required to recover specific data types, as mentioned earlier. For example, video recording a 

manual examination documents the recovery of evidence that the automated forensic tool did 

not acquire. Video editing software allows still images to be captured for inclusion into the 

report. Snapshots could also be taken of the manual exam using a digital camera, though the 

process is less efficient and does not document the entire process, nor allows the entire 

procedure to be viewed if questions arise. 

The type of data determines whether it is presentable in a hard-copy format. Today, many 

popular cellular devices are capable of capturing video and audio. Such evidentiary data (e.g., 

audio, video) cannot be presented in a printed format and instead should be included with the 

finalized report on removable media (e.g., CD-ROM, DVD-ROM, or thumb drive) along with 

the appropriate application for proper display. 

65
Guidelines on Cell Phone Forensics 

Reports of forensic examination results should include all the information necessary to identify 

the case and its source, outline the test results and findings, and bear the signature of the 

individual responsible for its contents. In general, the report may include the following 

information [DOJ04]: 

 Identity of the reporting agency 

 Case identifier or submission number 

 Case investigator 

 Identity of the submitter 

 Date of receipt 

 Date of report 

 Descriptive list of items submitted for examination, including serial number, make, 

and model 

 Identity and signature of the examiner 

 The equipment and set up used in the examination 

 Brief description of steps taken during examination, such as string searches, graphics 

image searches, and recovering erased files. 

 Supporting materials such as printouts of particular items of evidence, digital copies of 

evidence, and chain of custody documentation 

 Details of findings: 

 Specific files related to the request 

 Other files, including deleted files, that support the findings 

 String searches, keyword searches, and text string searches 

 Internet-related evidence, such as Web site traffic analysis, chat logs, cache files, 

e-mail, and news group activity 

 Graphic image analysis 

 Indicators of ownership, which could include program registration data 

 Data analysis 

 Description of relevant programs on the examined items 

66
Guidelines on Cell Phone Forensics 

 Techniques used to hide or mask data, such as encryption, steganography, hidden 

attributes, hidden partitions, and file name anomalies 

 Report conclusions 

Digital evidence, as well as the tools, techniques and methodologies used in an examination, is 

subject to being challenged in a court of law or other formal proceedings. Proper 

documentation is essential in providing individuals the ability to re-create the process from 

beginning to end. As part of the reporting process, making a copy of the software used and 

including it with the output produced is advisable. This is especially pertinent for custom 

tools, since confusion about the version of the software used to create the output is eliminated, 

should it become necessary to reproduce forensic processing results at a later time. The same 

practice applies to commercial software tools, which could be upgraded after an examination is 

completed [NTI]. 

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Guidelines on Cell Phone Forensics 

9. References 

[3GP02] 3GPP2 (2002), Removable User Identity Module for Spread Spectrum Systems, 3rd 

Generation Partnership Program 2, 3GPP2 C.S0023-A, Version 1.0, September 13, 

2002, <URL: http://www.3gpp2.org/public_html/specs/C.50023-A_v1.0.pdf>. 

[3GP05a] 3GPP (2005a), Specification of the Subscriber Identity Module - Mobile Equipment 

(SIM - ME) interface, 3rd Generation Partnership Project, TS 11.11 V8.13.0 

(Release 1999), Technical Specification, (2005-06). 

[3GP05b] 3GPP (2005b), Technical Realization of the Short Message Service (SMS), 3rd 

Generation Partnership Project, TS 23.040 V6.6.0 (Release 6), Technical 

Specification (2005-12). 

[3GP98] 3GPP (1999), Alphabets and Language-specific Information, 3rd Generation 

Partnership Project, TS 03.38, version 7.2.0 (Release 1998), Technical Specification 

(1999-07). 

[ACPO] Good Practice Guide for Computer-based Electronic Evidence, Association of 

Chief Police Officers, Version 3, <URL: 

http://www.acpo.police.uk/asp/policies/Data/gpg_computer_based_evidence_v3.pd

f >. 

[Aig] Manfred Aigner, Elisabeth Oswald, Power Analysis Tutorial, Seminar Paper, 

Institute for Applied Information Processing and Communication, <URL: 

http://www.iaik.tu-graz.ac.at/aboutus/people/oswald/papers/dpa_tutorial.pdf>. 

[Aja06] Ireti Ajala, Spatial Analysis of GSM Subscriber Call Data Records, Directions 

Magazine, Mar 07, 2006, <URL: 

http://www.directionsmag.com/article.php?article_id=2112&trv=1>. 

[Ala03] Searching Voicemail and E-mail, Point of View, Alameda County District 

Attorney's Office, Winter 2003, <URL: 

http://www.acgov.org/da/pov/documents/voicemail.pdf>. 

[Ala04] Phone, E-mail, and Internet Records, Point of View, Alameda County District 

Attorney's Office, Fall 2004, <URL: 

http://www.acgov.org/da/pov/documents/phone.pdf>. 

[Aye05] Rick Ayers, Wayne Jansen, Nicolas Cilleros, Ronan Daniellou, Cell Phone 

Forensics Tools: An Overview and Analysis, NIST Interagency Report (IR) 7250, 

October 2005, <URL: http://csrc.nist.gov/publications/nistir/nistir-7250.pdf>. 

[Aye07] Rick Ayers, Wayne Jansen, Aurelien Delaitre, Ludovic Moenner, Cell Phone 

Forensics Tools: An Overview and Analysis Update, NIST Interagency Report (IR) 

7387, February 2007<URL: http://csrc.nist.gov/publications/nistir/nistir-7387.pdf>. 

[Bre06] Breeuwsma, M. F., Forensic imaging of embedded systems using JTAG (boundaryscan), Digital Investigation, Volume 3, Issue 1, 2006, pp.32-42. 

68
Guidelines on Cell Phone Forensics 

[Bos05] Jeroen van den Bos, Ronald van der Knijf, TULP2G – An Open Source Forensic 

Software Framework for Acquiring and Decoding Data Stored in Electronic 

Devices, International Journal of Digital Evidence, Vol. 4, Issue 2, Fall 2005. 

[Bur02] Michael W. Burnette, Forensic Examination of a RIM (BlackBerry) Wireless 

Device, June 2002, <URL: https://www.rh-law.com/ediscovery/Blackberry.pdf>. 

[Bur05] Robert Burnett, Ylva Hård af Segerstad, The SMS Murder Mystery: the dark side of 

technology, Safety & Security in a Networked World: Balancing Cyber-Rights & 

Responsibilities, September 2005, <URL: 

http://www.oii.ox.ac.uk/microsites/cybersafety/extensions/pdfs/papers/robert_burne

tt.pdf>. 

[Car02] Brian Carrier, Defining Digital Forensic Examination and Analysis Tools, Digital 

Forensics Research Workshop II, August 2002, <URL: 

http://www.dfrws.org/dfrws2002/papers/Papers/Brian_carrier.pdf>. 

[Cas00] Eoghan Casey, Chapter 13: Forensic Examination of Handheld Devices, Digital 

Evidence and Computer Crime, Academic Press, March 2000. 

[Cas06] Casadei, F. et al., Forensics and SIM cards: an Overview, International Journal of 

Digital Evidence, Volume 5, Issue 1, Fall 2006, <URL: 

http://ieeexplore.ieee.org/iel5/10612/33521/01592525.pdf?isnumber=&arnumber=1

592525>. 

[Dea05] Dearsley, T., Mobile Phone Forensics – Asking the Right Questions, New Law 

Journal, July 29, 2005, pp. 1164-1165. 

[Dec93] Dechaux, C., Scheller, R., What are GSM and DECT?, Electrical Communication, 

2nd Quarter, 1993, pp. 118-127. 

[DOJ01] Electronic Crime Scene Investigation: A Guide for First Responders, U.S. 

Department of Justice, NCJ 187736, July 2001, <URL: 

http://www.ncjrs.org/pdffiles1/nij/187736.pdf>. 

[DOJ04] Forensic Examination of Digital Evidence: A Guide for Law Enforcement, U.S. 

Department of Justice, NCJ 199408, April 2004, <URL: 

http://www.ncjrs.org/pdffiles1/nij/199408.pdf>. 

[ETS99] Digital cellular telecommunications system (Phase 2) - Event and call data (GSM 

12.05 version 4.3.1), European Telecommunication Standard (ETS), ETSI TS 100 

616 V7.0.1, July 1999. 

[Gar01] You can ring, but you can't hide, The Guardian, November 29, 2001, <URL: 

http://technology.guardian.co.uk/online/story/0,,608434,00.html>. 

[Gas03] Ty Gast, Forensic Data Handling, Security Assurance Group, White Paper, 2003, 

<URL: http://www.securityassurancegroup.com/PDF/SAG-forensics-datahandling.PDF>. 

69
Guidelines on Cell Phone Forensics 

[Goo03] Amanda Goode, Forensic Extraction of Electronic Evidence from GSM Mobile 

Phones, IEE Seminar on Secure GSM & Beyond, Digest No. 2003/10059, February 

11, 2003. 

[Gra02] Joe Grand, pdd: Memory Imaging and Forensic Analysis of Palm OS Devices, 

Proceedings of the 14th Annual FIRST Conference on Computer Security 

Incident Handling and Response, June, 2002, <URL: 

http://www.first.org/events/progconf/2002/d3-04-grand-paper.pdf>. 

[GSM04] IMEI Allocation and Approval Guidelines, Version 3.3.0, GSM Association, 

Permanent Reference Document TW.06, December 2004, <URL: 

http://www.gsmworld.com/documents/twg/tw06.pdf>. 

[GSM05] GSME Position On Data Retention – Implications for The Mobile Industry, GSM 

Europe, GSM Association, 23 August 2005, <URL: 

http://www.gsmworld.com/gsmeurope/documents/positions/2005/gsme_position_d

ata_retention.pdf#search=%22GSME%20POSITION%20ON%20DATA%20RET

ENTION%22>. 

[Haa04] Job de Haas, Reverse Engineering ARM Based Devices, Black Hat Europe, May 

2004, <URL: https://www.blackhat.com/presentations/bh-europe-04/bh-eu-04-

dehaas/bh-eu-04-dehaas.pdf>. 

[Hin96] S. F. Hinde, Call Record Analysis, IEE Colloquium on Making Life Easier - 

Network Design and Management Tools, Digest No: 1996/216, 10 Oct 1996, pp. 

8/1-8/4, <URL: 

http://ieeexplore.ieee.org/iel3/5131/13951/00644775.pdf?isnumber=&arnumber=64

4775>. 

[Hos98] Chet Hosmer, Time Lining Computer Evidence, WetStone Technologies, Inc., 

1998, <URL: http://www.wetstonetech.com/f/timelining.pdf>. 

[Int96] Designing for On-Board Programming Using the IEEE 1149.1 (JTAG) Access 

Port, Intel, Application Note, AP-630, November 1996, <URL: 

http://www.intel.com/design/flcomp/applnots/29218602.PDF>. 

[Its] XDA Bootloader, ITSX, <URL: http://www.itsx.com/index.html?pocketpcbootloader.html~mainFrame>. 

[ITU06] ITU-T (2006), Automatic International Telephone Credit Cards, International 

Telecommunications Union, Telecommunication Standardization Sector (ITU-T), 

Recommendation E.118, (02/01). 

[INT06] Mobile Phone Forensics, 47th EWPITC meeting – Final report, European Working 

Party on IT Crime, INTERPOL, September 7, 2006. 

[IOCE] Digital Evidence: Standards and Principles, Scientific Working Group on Digital 

Evidence (SWGDE), International Organization on Computer Evidence (IOCE), 

Forensic Science Communications, Vol. 2, No. 2, April 2000, <URL: 

http://www.fbi.gov/hq/lab/fsc/backissu/april2000/swgde.htm>. 

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Guidelines on Cell Phone Forensics 

[Jan06] Wayne Jansen, Rick Ayers, Forensic Software Tools for Cell Phone Subscriber 

Identity Modules, Conference on Digital Forensics, Association of Digital 

Forensics, Security, and Law (ADFSL), April 2006, <URL: 

http://csrc.nist.gov/mobilesecurity/publication/pp-SIM%20tools-final.pdf>. 

[Kin01] Joe Grand (Kingpin) and Mudge, Security Analysis of the Palm Operating System 

and its Weaknesses Against Malicious Code Threats, August 2001, pp. 135-152, 

Proceedings of the 10th Usenix Security Symposium, <URL: 

http://www.usenix.org/events/sec01/full_papers/kingpin/kingpin_html>. 

[Kni02] Ronald van der Knijff, Chapter 11: Embedded Systems Analysis, Handbook of 

Computer Crime Investigation, Edited by Eoghan Casey, Academic Press, 2002. 

[Ko96] Y. F. Ko, Automatic Call Generation and Analysis - Network Testing and Cellular 

Survey Tools, IEE Colloquium on Making Life Easier - Network Design and 

Management Tools, Digest No: 1996/217, 10 Oct. 1996, pp. 7/1 - 7/6, <URL: 

http://ieeexplore.ieee.org/iel3/5131/13951/00644774.pdf?tp=&arnumber=644774&

isnumber=13951>. 

[Kru01] Warren G. Kruse II, Jay G. Heiser, Computer Forensics – Incident Response 

Essentials, Pearson Education, September 26, 2001. 

[Ley01] John Leyden, How to crash a phone by SMS, The Register, November 2001, 

<URL: http://www.theregister.co.uk/2001/11/28/how_to_crash_a_phone/> 

[Man01] Kevin Mandia, Chris Prosise, Incident Response: Investigating Computer Crime, 

McGrawHill Osborne Media, 2001. 

[Mcc05] Paul McCarthy, Forensic Analysis of Mobile Phones, BS CIS Thesis, University of 

South Australia, School of Computer and Information Science, Mawson Lakes, 

October 2005, <URL: 

http://esm.cis.unisa.edu.au/new_esml/resources/publications/forensic%20analysis%

20of%20mobile%20phones.pdf>. 

[Mcc06] Paul McCarthy, Jill Slay, Mobile phones: admissibility of current forensic 

procedures for acquiring data, the Second IFIP WG 11.9 International Conference 

on Digital Forensics, 2006. 

[Mel04] Barrie Mellars, Forensic Examination of Mobile Phones, Digital Investigation, 

Vol.1, No. 4, 2004, pp. 266-272. 

[Meu02] Pascal Meunier, Sofie Nystrom, Seny Kamara, Scott Yost, Kyle Alexander, Dan 

Noland, Jared Crane, ActiveSync, TCP/IP and 802.11b Wireless Vulnerabilities of 

WinCE-based PDAs, Proceedings of the Eleventh IEEE International Workshops 

on Enabling Technologies: Infrastructure for Collaborative Enterprises 

(WETICE’02), June 2002, <URL: http://www.cs.nmt.edu/~cs553/paper3.pdf or 

http://www.cs.jhu.edu/~seny/pubs/wince802.pdf>. 

[Moo06] Tyler Moore, The Economics of Digital Forensics, Fifth Annual Workshop on the 

Economics and Information Security, June 2006, <URL: 

http://www.cl.cam.ac.uk/~twm29/weis06-moore.pdf>. 

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Guidelines on Cell Phone Forensics 

[New07] Annalee Newitz, Courts Cast Wary Eye on Evidence Gleaned From Cell Phones, 

WIRED, May 10, 2007, <URL: 

http://www.wired.com/politics/law/news/2007/05/cellphone_forensics>. 

[NIJ05] No More ‘Cell’ Phones, TechBeat, Winter 2005, National Law Enforcement and 

Corrections Technology Center, <URL: 

http://www.nlectc.org/techbeat/winter2005/NoMoreCellPhones.pdf>. 

[Nok05] AT Command Set for Nokia GSM and WCDMA Products, Version 1.2, Nokia 

Corporation, July 2005, <URL: http://sw.nokia.com/id/95672052-6c77-488d-a055-

acef77e4cdc5/AT_Command_Set_For_Nokia_GSM_And_WCDMA_Products_v1

_2_en.pdf>. 

[NTI] Computer Evidence Processing Steps, New Technologies Inc., <URL: 

http://www.forensics-intl.com/evidguid.html>. 

[Oco04] Thomas R. O'connor, Admissibility of Scientific Evidence Under Daubert, North 

Carolina Wesleyan College, March 2004, <URL: 

http://faculty.ncwc.edu/toconnor/daubert.htm>. 

[Pie99] Claire Pieterek, How to get an extra 824K using FlashPro, PalmPower Magazine, 

May 1999, <URL: 

http://www.palmpower.com/issues/issue199905/flashpro001.html>. 

[Pea05] Wayne Peacock, An Introduction to Nokia F-bus, April 2005, <URL: 

http://www,embedtronics.com/nokia/fbus.html>. 

[Pmd02] Palm Security, How-To Guide, pdaMD.com, 2002, <URL: 

http://www.pdamd.com/vertical/tutorials/palmsecure.xml>. 

[PPC04] Palm OS Programmer's Companion, Volume I, PalmSource, Inc., May 2004, 

<URL: http://www.palmos.com/dev/support/docs/palmos/CompanionTOC.html>. 

[Pur] Stephen R. Purdy, The Reality of Computer Forensics: Electronic Evidence 

Discovery and Recovery, Agile Risk Management Group LLC. 

[Rei02] Mark Reith, Clint Carr, and Gregg Gunsch, An Examination of Digital Forensic 

Models, International Journal of Digital Evidence, Fall 2002, Volume 1, Issue 3 

<URL: http://www.ijde.org/docs/02_fall_art2.pdf>. 

[Sha06] Noah Shachtman Fighting Crime with Cellphones' Clues, NY Times, May 3, 2006, 

<URL: http://www.mobileforensicstraining.com/inthenews_main.html>. 

[Smi05] Greg Smith, Switch On ~ Update = Lose Evidence, Mobile Telephone Evidence 

Newsletter, INDEX NO: VOL 4-MTE05- 2006, Trew & Co, 2005, <URL: 

http://filebucket.org/files/7019_h66bf/Switch%20On%20Update%20Lose%20Evid

ence>. 

[Smi06] Greg Smith, Handset Password Unlock, Mobile Telephone Evidence Newsletter, 

INDEX NO: VOL 4-MTE03- 2006 supp: 002, Trew & Co, 2006. 

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Guidelines on Cell Phone Forensics 

[Sum03] Chris Summers, Mobile phones - the new fingerprints, BBC News Online, 

December 18, 2003, <URL: 

http://newsvote.bbc.co.uk/mpapps/pagetools/print/news.bbc.co.uk/1/hi/uk/3303637.

stm>. 

[Vam07] Robert Vamosi, Cell Phone ‘CSI,’ CNET Reviews, May 25, 2007, ,URL: 

http://reviews.cnet.com/4520-3513_7-6737586-1.htm>. 

[Ved93] Vedder, K., 1993, Security Aspects of Mobile Communications, in Computer 

Security and Industrial Cryptography - State of the Art and Evolution, Lecture 

Notes in Computer Science, Vol. 741, pp. 193-210. 

[Wie02] Officer Fred J.Wiechmann, Processing Flash Memory Media, New Technologies 

Inc., November 2002, <URL: http://www.forensics-intl.com/art16.html>. 

[Wil03] Svein Willassen, Forensics and the GSM Mobile Telephone System, International 

Journal of Digital Evidence, Volume 2, Issue 1, 2003, <URL: 

http://www.utica.edu/academic/institutes/ecii/publications/articles/A0658858-

BFF6-C537-7CF86A78D6DE746D.pdf>. 

[Wil05] Svein Willassen, Forensic Analysis of Mobile Phone Internal Memory, IFIP WG 

11.9 International Conference on Digital Forensics, National Center for Forensic 

Science, Orlando, Florida, February 13-16, 2005, in Advances in Digital Forensics, 

Vol. 194, Pollitt, M.; Shenoi, S. (Eds.), XVIII, 313 p., 2006. 

[Wol03] Henry B.Wolfe, Evidence Analysis, Computers and Security, May 2003, Volume 

22, Issue 4, pp. 289-291, <URL: 

http://www.sparksdata.co.uk/elseforms/order/COSE%202201.pdf>. 

[Wyl00] Margie Wylie, Cell Phone Jammers, Illegal in U.S., Can Create Silent Zones, 

Newhouse News Service, 2000, <URL: 

http://www.newhousenews.com/archive/story1a092200.html>. 

[Xjt03] JTAG testing with XJTAG, Version 0.1, XJTAG, March 2003, <URL: 

http://www.xjtag.com/images/TestingWithXJTAG.pdf>. 

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Appendix A. Acronyms 

APDU – Application Protocol Data Unit 

API – Application Programming Interface 

ASCII – American Standard Code for Information Interchange 

BCD – Binary Coded Decimal 

BSC – Base Station Controller 

BTS – Base Transceiver Station 

CDMA – Code Division Multiple Access 

CF – Compact Flash 

EDGE – Enhanced Data for GSM Evolution

EMS – Enhanced Messaging Service

ESN – Electronic Serial Number 

FCC ID – Federal Communications Commission Identification Number

GPRS – General Packet Radio Service 

GPS – Global Positioning System 

GSM – Global System for Mobile Communications 

HTTP – HyperText Transfer Protocol 

ICCID – Integrated Circuit Card Identification 

IDE – Integrated Drive Electronics 

iDEN – Integrated Digital Enhanced Network

IM – Instant Messaging

IMAP – Internet Message Access Protocol

IMEI – International Mobile Equipment Identity

IMSI – International Mobile Subscriber Identity

IrDA – Infra Red Data Association 

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JTAG – Joint Test Action Group 

LCD – Liquid Crystal Display 

LED – Light Emitting Diode 

MD5 – Message Digest 5 

MMC – Multi-Media Card 

MMS – Multimedia Messaging Service

MSC – Mobile Switching Center 

MSISDN – Mobile Subscriber Integrated Services Digital Network

OS – Operating System 

PC – Personal Computer 

PDA – Personal Digital Assistant 

PIM – Personal Information Management 

PIN – Personal Identification Number 

POP – Post Office Protocol

RAM – Random Access Memory 

ROM – Read Only Memory 

SD – Secure Digital 

SDK – Software Development Kit 

SHA1 – Secure Hash Algorithm, version 1 

SIM – Subscriber Identity Module

SMS – Short Message Service

SMTP – Simple Mail Transfer Protocol

TCP/IP – Transmission Control Protocol/Internet Protocol 

TDMA – Time Division Multiple Access 

UMTS – Universal Mobile Telecommunications System 

URL – Uniform Resource Locator 

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USB – Universal Serial Bus 

USIM – UMTS Subscriber Identity Module

WAP – Wireless Application Protocol

WiFi – Wireless Fidelity 

XHTML – Extensible HyperText Markup Language 

XML – Extensible Markup Language 

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Appendix B. Glossary 

Acquisition – A process by which digital evidence is duplicated, copied, or imaged. 

Analysis – The examination of acquired data for its significance and probative value to the 

case. 

Authentication Mechanism – Hardware or software-based mechanisms that force users to 

prove their identity before accessing data on a device. 

Bluetooth – A wireless protocol that allows two Bluetooth enabled devices to communicate 

with each other within a short distance (e.g., 30 ft.). 

Brute Force Password Attack – A method of accessing an obstructed device by attempting 

multiple combinations of numeric/alphanumeric passwords. 

Buffer Overflow Attack – A method of overloading a predefined amount of space in a buffer, 

which can potentially overwrite and corrupt memory in data. 

Chain of Custody – A process that tracks the movement of evidence through its collection, 

safeguarding, and analysis lifecycle by documenting each person who handled the evidence, 

the date/time it was collected or transferred, and the purpose for the transfer. 

Code Division Multiple Access (CDMA) – A spread spectrum technology for cellular 

networks based on the Interim Standard-95 (IS-95) from the Telecommunications Industry 

Association (TIA). 

Compressed File – A file reduced in size through the application of a compression algorithm, 

commonly performed to save disk space. The act of compressing a file will make it 

unreadable to most programs until the file is uncompressed. Most common compression 

utilities are PKZIP and WinZip, which produce files with an extension of .zip. 

Cradle – A docking station, which creates an interface between a user’s PC and PDA, and 

enables communication and battery recharging. 

Cyclical Redundancy Check – A method to ensure data has not been altered after being sent 

through a communication channel. 

Deleted File – A file that has been logically, but not necessarily physically, erased from the 

operating system, perhaps to eliminate potentially incriminating evidence. Deleting files does 

not always necessarily eliminate the possibility of recovering all or part of the original data. 

Digital Evidence – Electronic information stored or transmitted in binary form. 

Duplicate Digital Evidence – A duplicate is an accurate digital reproduction of all data 

objects contained on the original physical item and associated media (e.g., flash memory, 

RAM, ROM). 

Electromagnetic Interference – An electromagnetic disturbance that interrupts, obstructs, or 

otherwise degrades or limits the effective performance of electronics/electrical equipment. 

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Electronic Evidence – Information and data of investigative value that is stored on or 

transmitted by an electronic device. 

Electronic Serial Number (ESN) – A unique 32-bit number programmed into CDMA 

phones when they are manufactured.

Encryption – Any procedure used in cryptography to convert plain text into cipher text to 

prevent anyone but the intended recipient from reading that data. 

Enhanced Data for GSM Evolution (EDGE) – An upgrade to GPRS to provide higher data 

rates by joining multiple time slots. 

Enhanced Messaging Service (EMS) – An improved message system for GSM mobile 

phones allowing picture, sound, animation and text elements to be conveyed through one or 

more concatenated SMS messages. 

Examination – A technical review that makes the evidence visible and suitable for analysis; 

tests performed on the evidence to determine the presence or absence of specific data. 

Exculpatory Evidence – Evidence that tends to decrease the likelihood of fault or guilt.

Extensible HyperText Markup Language (XHTML) – A unifying standard that brings the 

benefits of XML to those of HTML. 

Extensible Markup Language (XML) – A flexible text format designed to describe data for 

electronic publishing. 

File Name Anomaly – A mismatch between the internal file header and its external file name 

extension; a file name inconsistent with the content of the file (e.g., renaming a graphics file 

with a non-graphics extension). 

File System – A software mechanism that defines the way that files are named, stored, 

organized, and accessed on logical volumes of partitioned memory. 

Flash ROM – Non-volatile memory that is writable. 

Forbidden PLMNs – A list of Public Land Mobile Networks (PLMNs) maintained on the 

SIM that the phone cannot automatically contact, usually because service was declined by a 

foreign provider. 

Forensic Copy – An accurate bit-for-bit reproduction of the information contained on an 

electronic device or associated media, whose validity and integrity has been verified using an 

accepted algorithm. 

Forensic Specialist – Locates, identifies, collects, analyzes and examines data while 

preserving the integrity and maintaining a strict chain of custody of information discovered. 

General Packet Radio Service (GPRS) – A packet switching enhancement to GSM and 

TDMA wireless networks to increase data transmission speeds. 

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Global Positioning System – A system for determining position by comparing radio signals 

from several satellites. 

Global System for Mobile Communications (GSM) – A set of standards for second 

generation, cellular networks currently maintained by the 3rd Generation Partnership Project 

(3GPP).

Hardware Driver – Applications responsible for establishing communication between 

hardware and software programs. 

Hashing – The process of using a mathematical algorithm against data to produce a numeric 

value that is representative of that data. 

HyperText Transfer Protocol (HTTP) – A standard method for communication between 

clients and Web servers. 

Image – An exact bit-stream copy of all electronic data on a device, performed in a manner 

that ensures the information is not altered. 

Inculpatory Evidence – Evidence that tends to increase the likelihood of fault or guilt.

Instant Messaging (IM) – A facility for exchanging messages in real-time with other people 

over the Internet and tracking the progress of the conversation. 

Integrated Circuit Card ID (ICCID) – The unique serial number assigned to, maintained 

within, and usually imprinted on the (U)SIM. 

Integrated Digital Enhanced Network (iDEN) – A proprietary mobile communications 

technology developed by Motorola that combine the capabilities of a digital cellular telephone 

with two-way radio. 

International Mobile Equipment Identity (IMEI) – A unique identification number 

programmed into GSM and UMTS mobile phones. 

International Mobile Subscriber Identity (IMSI) – A unique number associated with every 

GSM mobile phone subscriber, which is maintained on a (U)SIM. 

Internet Message Access Protocol (IMAP) – A method of communication used to read 

electronic messages stored in a remote server. 

Location Information (LOCI) – The Location Area Identifier (LAI) of the phone’s current 

location, continuously maintained on the (U)SIM when the phone is active and saved 

whenever the phone is turned off.

Misnamed Files – A technique used to disguise a file’s content by changing the file’s name to 

something innocuous or altering its extension to a different type of file, forcing the examiner to 

identify the files by file signature versus file extension. 

Mobile Subscriber Integrated Services Digital Network (MSISDN) – The international 

telephone number assigned to a cellular subscriber.

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Multimedia Messaging Service (MMS) – An accepted standard for messaging that lets users 

send and receive messages formatted with text, graphics, photographs, audio, and video clips. 

Password Protected – The ability to protect the contents of a file or device from being 

accessed until the correct password is entered. 

Personal Digital Assistant (PDA) – A handheld computer that serves as a tool for reading and 

conveying documents, electronic mail, and other electronic media over a communications link, 

and for organizing personal information, such as a name-and-address database, a to-do list, and 

an appointment calendar. 

Personal Information Management (PIM) Applications – A core set of applications that 

provide the electronic equivalents of such items as an agenda, address book, notepad, and 

reminder list. 

Personal Information Management (PIM) Data – The set of data types such as contacts, 

calendar entries, phonebook entries, notes, memos, and reminders maintained on a device, 

which may be synchronized with a personal computer. 

Post Office Protocol (POP) – A standard protocol used to receive electronic mail from a 

server. 

Probative Data – Information that reveals the truth of an allegation. 

Short Message Service (SMS) – A cellular network facility that allows users to send and 

receive text messages of up to 160 alphanumeric characters on their handset. 

Simple Mail Transfer Protocol (SMTP) – The primary protocol used to transfer electronic 

mail messages on the Internet. 

SMS Chat – A facility for exchanging messages in real-time using SMS text messaging that 

allows previously exchanged messages to be viewed. 

Steganography – The art and science of communicating in a way that hides the existence of 

the communication. For example, a child pornography image can be hidden inside another 

graphic image file, audio file, or other file format. 

Subscriber Identity Module (SIM) – A smart card chip specialized for use in GSM 

equipment. 

Synchronization Protocols – Protocols that allow users to view, modify, and transfer/update 

data between a cell phone and personal computer. 

UMTS Subscriber Identity Module (USIM) – A module similar to the SIM in GSM/GPRS 

networks, but with additional capabilities suited to 3G networks. 

Universal Mobile Telecommunications System (UMTS) – A third-generation (3G) mobile 

phone technology standardized by the 3GPP as the successor to GSM. 

Universal Serial Bus (USB) – A hardware interface for low-speed peripherals such as the 

keyboard, mouse, joystick, scanner, printer, and telephony devices. 

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Volatile Memory – Memory that loses its content when power is turned off or lost. 

Wireless Application Protocol (WAP) – A standard that defines the way in which Internet 

communications and other advanced services are provided on wireless mobile devices.

Wireless Fidelity (WiFi) – A term describing a wireless local area network that observes the 

IEEE 802.11 protocol.

Write-Blocker – A device that allows investigators to examine media while preventing data 

writes from occurring on the subject media. 

Write Protection – Hardware or software methods of preventing data from being written to a 

disk or other medium. 

Extensible HyperText Markup Language (XHTML) – A unifying standard that brings the 

benefits of XML to those of HTML. 

Extensible Markup Language (XML) – A flexible text format designed to describe data for 

electronic publishing. 

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Appendix C. Generic Acquisition Overview 

This appendix gives an overview of the acquisition of a mobile phone and (U)SIM. Most tools 

have an acquisition wizard that guides one successfully through the process. An idealized 

explanation of the steps involved is outlined below, illustrated using excerpts of screen shots 

taken from a number of different tools. 

C.1 Connection Identification 

The initial step is identifying the type of connection to use. The three choices often offered are 

connecting via a cable, an infrared interface, or a Bluetooth interface, as shown in Figure 7. 

Generally, the order listed is the preferred order of selection. However, other forensic issues 

may exist for the connection type when used with a particular device. The tool manufacturer’s 

user guide and Web site or an independent tool guidance database can sometimes be checked 

for clarification. 

Figure 7: Connection Identification 

C.2 Device Identification 

Once the type of connection being used is determined, the device can be identified. Often this 

is done through the manufacturer name and device model number. Some tools may attempt to 

identify the device automatically. Note that some toolkits, such as the one shown in Figure 8, 

support both phone and (U)SIM acquisition and offer both choices. 

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Figure 8: Device Acquisition 

C.3 Data Selection 

Most tools offer a choice of recovering a subset of the data expected to be recovered, such as 

that illustrated in Figure 9. That option might be useful if the reporting capabilities of the tool 

automatically generate a report of all items acquired. Alternatively, performing a complete 

acquisition may be reasonable if the reporting capabilities of the tool allow the selected items 

of interest to be selectively reported. One side benefit with this approach is that the case file 

can be maintained and referenced later, if additional types of information are needed. 

Note that the recoverable items listed can differ among mobile phones, depending on the 

phone’s capabilities. Note too that forensic issues may exist that might oblige one to skip 

recovery of a particular item. 

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Guidelines on Cell Phone Forensics 

Figure 9: Data Selection 

C.4 Acquisition 

After the data to recover is selected, acquisition begins. Acquisition may proceed quietly with 

a progress bar or more informatively with a viewable log of the progress. The latter is 

illustrated in Figure 10, which shows a summary of the different protocols being attempted 

(i.e., AT commands defined in a GSM standard and proprietary FBUS commands) and the 

status of the attempts made. 

While high level logs are informative, some tools can also capture a detailed log of the entire 

acquisition. Detailed logs can be useful in a number of ways: they may provide information to 

the tool manufacturer if the tool fails; they can confirm that the protocol commands were of a 

read-only nature; and they may occasionally contain useful forensic data not reported by the 

tool. 

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Guidelines on Cell Phone Forensics 

Figure 10: Acquisition 

Upon completion of the acquisition, some arrangement of the recovered data is made available 

for selection. The items for selection are commonly presented in the form of tabbed displays 

or a hierarchical tree structure. 

C.5 Phonebook Entries 

Phonebook entries may contain more than just names and phone numbers, including such 

things as email and postal addresses, as shown in Figure 11. Some camera phones can also 

store and display a photo of individuals along with their contact information. 

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Guidelines on Cell Phone Forensics 

Figure 11: Phonebook Entries 

C.6 Call Log Entries 

Phone logs capture the set of recent calls attempted from the phone, received by the phone, and 

missed by the phone, as illustrated in Figure 12. 

Figure 12: Call Log Entries 

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Guidelines on Cell Phone Forensics 

C.7 Message Entries 

Message entries include both text and multimedia messages received and sent by the phone. 

Figure 13 illustrates some simple text message entries, while Figure 14 illustrates some 

multimedia message entries. 

Figure 13: SMS Text Messages 

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Guidelines on Cell Phone Forensics 

Figure 14: Multimedia Message 

C.8 Calendar Entries 

Calendar entries are sometimes known as appointment books. Similar to a paper agenda 

carried by individuals, calendar entries provide an electronic counterpart, maintaining the date 

and time of some scheduled event. Figure 15 illustrates a calendar page containing active 

entries. 

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Guidelines on Cell Phone Forensics 

Figure 15: Calendar Entries 

C.9 (U)SIM Data 

(U)SIM data may be acquired in two ways: indirectly through commands sent to the phone 

and passed on to the (U)SIM or directly through commands sent to a (U)SIM reader into 

which the (U)SIM is placed. Figure 16 illustrates the latter. This presumes, of course, that the 

device identification selection made for the acquisition was a GSM SIM card instead of a 

mobile phone. 

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Guidelines on Cell Phone Forensics 

Figure 16: (U)SIM Data 

The hierarchical tree structure at the upper left reflects the file system of the (U)SIM. The 

contents of highlighted item selected in the tree structure (i.e., SMS text messages) are shown 

at the upper right and also in the window below. 

C.10 Picture Entries 

Many mobile phones have a built-in camera and are capable of receiving messages containing 

photos. The photos taken can reside in the memory of the phone or in removable memory 

cards present in the device. Figure 17 illustrates a gallery of the images found on a mobile 

phone collected together for examination and displayed as thumbnail images. 

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Figure 17: Picture Entries 

C.11 Searching 

Searching for a specific name or number within a body of digital evidence can be aided with a 

search facility. Figure 18 illustrates a simple name search. A tool may be able to control the 

scope of a search to include the current case file, a portion of the case file, or a set of case files. 

Figure 18: Search Facility 

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Guidelines on Cell Phone Forensics 

C.12 Reporting 

Reporting allows the generation of a report in a variety of formats, as shown in Figure 19. 

Other formats that may be supported by a tool’s report facility include XML and Microsoft 

Word. The report facility may also support tailoring of the report output to include laboratory 

names and logos and information acquired elsewhere, such as photos of the device at seizure 

or at receipt by the laboratory. 

Figure 19: Report Facility 

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Guidelines on Cell Phone Forensics 

Appendix D. Standardized Call Records 

The European Telecommunications Standards Institute specification for GSM event and call 

data provides detailed definitions for a variety of records needed in the administration of 

subscriber related event and call data. Table 7 gives the record structure for a mobileoriginated call attempt, identifying and describing the name of the various fields involved and 

an indication of whether the field is mandatory (M), conditional (C), or optional (O). 

Other record definitions also appear in the standard. The reader is asked to consult the 

standard directly for a more detailed explanation of the use of each field given in Table 7 and a 

better understanding of the range of records and data involved in network administration. 

Table 7: Example Record Structure 

Field Key Description 

Record Type M Mobile originated 

Served IMSI M IMSI of the calling party 

Served IMEI C IMEI of the calling ME, if available 

Served MSISDN O The primary MSISDN of the calling party 

Called Number M The address of the called party, e.g., the number dialed by the 

calling subscriber 

Translated Number O The called number after digit translation within the MSC (if 

applicable) 

Connected Number O The number of the connected party if different from the Called 

Number 

Roaming Number O The Mobile Station Roaming Number employed to route this 

connection, if applicable 

Recording Entity M The E.164 number of the visited MSC producing the record 

Incoming TKGP O The MSC trunk group on which the call originated, usually from 

the BSS 

Outgoing TKGP O The trunk group on which the call left the MSC 

Location M The identity of the cell in which the call originated including the 

location area code 

Change of Location O A list of changes in Location Area Code / Cell Id., each timestamped 

Basic Service M Bearer or teleservice employed 

Transparency Indicator C Only provided for those teleservices which may be employed in 

both transparent and non-transparent mode 

ChangeOfService O A list of changes of basic service during a connection each timestamped 

Supp. Services C Supplementary services invoked as a result of this connection 

AOC Parameters O The charge advice parameters sent to the MS on call setup 

Change of AOC Parms O New AOC parameters sent to the MS, e.g., as a result of a tariff 

switch over, including the time at which the new set was applied 

MS Classmark M The mobile station classmark employed on call setup 

Change of Classmark O A list of changes to the classmark during the connection, each 

time-stamped 

Event Time Stamps C 

C 

O 

Seizure of incoming traffic channel (for unsuccessful call attempts) 

Answer (for successful calls) 

Release of traffic channel 

Call Duration M The chargeable duration of the connection for successful calls, the 

holding time for call attempts 

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Guidelines on Cell Phone Forensics 

Radio Chan. Requested O The type of radio traffic channel (full / half etc.) requested by the 

MS 

Radio Chan. Used M The type of radio channel actually used (full or half rate) 

Change of Rad. Chan. O A list of changes, each timestamped 

Cause for Termination M The reason for the release of the connection 

Diagnostics O A more detailed reason for the release of the connection 

Data Volume C The number of data segments transmitted, if available at the MSC 

Sequence No. C Partial record sequence number, only present in case of partial 

records 

Call Reference M A local identifier distinguishing between transactions on the same 

MS 

Additional Chg. Info O Charge/no charge indicator and additional charging parameters 

Record Extensions O A set of network/manufacturer specific extensions to the record 

gsmSCF address C Identifies the CAMEL server serving the subscriber 

Service Key C The CAMEL service logic to be applied 

Network Call Reference C An identifier to correlate transactions on the same call taking place 

in different network nodes, shall be present if CAMEL is applied 

MSC Address C This field contains the E.164 number assigned to the MSC that 

generated the network call reference 

Default Call Handling O Indicates whether or not a CAMEL call encountered default call 

handling – Shall be present only if default call handling has been 

applied 

Number of HSCSD 

Channels Requested 

C The maximum number of HSCSD channels requested as 

received from the MS at call set-up 

Number of HSCSD 

Channels Allocated 

C The number of HSCSD channels allocated to the MS at call set-up 

Change of HSCSD 

Parameters 

C A list of network or user initiated changes of number of HSCSD 

channels during a connection, each timestamped – Shall only be 

present in case of an HSCSD call, if the basic HSCSD parameters 

are modified due to the user or network initiated modification 

procedure 

Fixed Network User 

Rate 

O May be present for HSCSD connections 

Air Interface User Rate 

Requested 

C The total Air Interface User Rate Requested by the MS at call 

setup. Shall only be present for non-transparent HSCSD 

connections 

Channel Coding 

Accepted 

C A list of the traffic channels codings accepted by the MS – Shall 

only be present for HSCSD connections 

Channel Coding Used C The traffic channels codings negotiated between the MS and the 

network at call setup – Shall only be present for HSCSD 

connections 

Speech Version Used O Speech version used for that call 

Speech Version 

Supported 

O Speech version supported by the MS with highest priority 

indicated by MS 

Number of DP 

Encountered 

O Number that counts how often armed detection points (TDP and 

EDP) were encountered 

Level of CAMEL service O Indicator for the complexity of the CAMEL feature used 

Free format Data C This field contains data sent by the gsmSCF in the FCI message 

CAMEL Call Leg 

Information 

C Set of CAMEL information IEs. Each of these IEs contains 

information related to one outgoing CAMEL call leg 

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Appendix E. Online Resources for Mobile Device Forensics 

This appendix contains lists of online resources that may be useful to incident response 

communities and law enforcement when mobile devices are encountered during an incident or 

crime. The resources provide additional information on aspects of cell phone forensics. 

Table 8: Technical Resource Sites 

Resource URL 

The Electronic Evidence Information 

Center 

http://www.e-evidence.info/cellular.html

High Tech Crime Consortium mail 

list 

https://htcc.secport.com/mailman/listinfo/htcc

Phone Forensics Portal http://www.phone-forensics.com/forum/portal.php

Phone Forensics Group http://groups.yahoo.com/group/phoneforensics/

SEARCH: Investigator’s Toolkit http://www.search.org/files/pdf/CellphoneInvestToolkit-0806.pdf

The Netherlands Forensic Institute’s 

procedures for preservation 

http://www.holmes.nl/MPF/FlowChartForensicMobilePhoneExa

mination.htm

Secure Digital Homepage http://www.Sdcard.org

Multi-Media Card Homepage http://www.mmca.org

CDMA Documents http://www.tiaonline.org/standards/technology/cdma2000/cdma

2000table.cfm

Table 9: Databases for Identification Queries 

Resource URL 

Device Characteristics http://www.phonescoop.com/phones/finder.php

http://www.gsmarena.com/search.php3

http://mobile.softpedia.com/phoneFinder

IMEI Queries http://www.numberingplans.com/?page=analysis&sub=imeinr

Manufacturer Codes http://www.tiaonline.org/standards/resources/esn/codes.cfm

ICCID Queries http://www.numberingplans.com/?page=analysis&sub=simnr

FCCID Queries http://www.fcc.gov/oet/fccid/

Phone Carrier Finder http://www.fonefinder.net/

Phone Number Carrier Lookup www.npac.com

Table 10: Forensic Tools 

Resource URL 

Forensic Card Reader http://www.becker-partner.de/forensic/intro_e.htm

ForensicSIM http://www.radio-tactics.com

SIMCon http://www.simcon.no

SIMIS http://www.crownhillmobile.com

USIMdetective http://www.quantaq.com/

BitPIM http://www.bitpim.org

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Guidelines on Cell Phone Forensics 

Resource URL 

Oxygen PM

(forensic version) 

http://www.opm-2.com/forensic

Oxygen PM for Symbian (forensic 

version) 

http://www.opm-2.com/forensic

PDA Seizure http://www.paraben-forensics.com

Pilot-Link http://www.pilot-link.org

Cell Seizure http://www.paraben-forensics.com

CellDEK http://www.logicubeforensic.com

GSM .XRY http://www.msab.com

MobilEdit! http://www.mobiledit.com

PhoneBase http://www.phonebase.info

Secure View http://www.susteen.com

TULP 2G http://tulp2g.sourceforge.net

SIMgen http://www.3gforensics.co.uk/simgen.html

Table 11: Other Related Tools 

Resource URL 

CSurv http://www.teeltech.com/tt/TeelTechCsurv.pdf.pdf

Cell View http://www.icardforensics.com/documents/CellSiteMonitor.pdf

Port Monitoring Utilities http://www.sysinternals.com/Utilities/Portmon.html

http://www.hhdsoftware.com/sermon.html

Master Unlock Code Calculator http://www.fonefunshop.co.uk/Unlocking/nokiasecuritycode.ht

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