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NIST Special Publication 800-30

Risk Management Guide for Information Technology Systems

July 2002

September 2012

SP 800-30 is superseded in its entirety by the publication of

SP 800-30 Revision 1 (September 2012).

NIST Special Publication 800-30 Revision 1

Guide for Conducting Risk Assessments

Joint Task Force Transformation Initiative

September 2012

http://dx.doi.org/10.6028/NIST.SP.800-30r1

Computer Security Division (Information Technology Lab)

SP 800-30 Revision 1 (as of June 19, 2015)

http://csrc.nist.gov/

N/A
NATL INST. OF STAND & TECH

I

NISI

PUBUCATSOt^S

National Institute of

Standards and Technology

Technology Administration

U.S. Department of Commerce

NIST Special Publication

800-30

Risk Management Guide

for Information Technology

Systems

Recommendations of the National Institute

of Standards and Technology

Gary Stoneburner, Alice Goguen, and

Alexis Feringa

COMPUTER SECURITY
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2Some elements at Boulder, CO.
NisT Special Publication 800-30 Risk Management Guide

for Information Technology

Systems

Recommendations ofthe National Institute

of Standards and Technology

Gary Stoneburner, Alice Goguen, and

Alexis Feringa

COMPUTER SECURITY

Computer Security Division

Information Technology Laboratory

National Institute of Standards and Technology

Gaithersburg, MD 20899-8930

July 2002

U.S. Department of Commerce

Donald L. Evans, Secretary

Technology Administration

Phillip J. Bond, Under Secretary of Commercefor Technology

National Institute of Standards and Technology

Arden L. Bement, Jr., Director
Reports on Information Security 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 analyses 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 800-30

Natl. Inst. Stand. Technol. Spec. Publ. 800-30, 54 pages (July 2002)

CODEN: NSPUE2

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 2002

For sale by the Superintendent of Documents, U.S. Government Printing Office

Internet: bookstore.gpo.gov —Phone: (202) 5 1 2- 1 800 —Fax: (202) 5 1 2-2250

Mail: Stop SSOP Washington, DC 20402-0001
Acknowledgements

The authors, Gary Stonebumer from NIST and Ahce Goguen and Alexis Feringa from Booz

Allen Hamilton, wish to express their thanks to their colleagues at both organizations who

reviewed drafts of this document. In particular, Timothy Grance, Marianne Swanson, and Joan

Hash from NIST and Debra L. Banning, Jeffrey Confer, Randall K. Ewell, and Waseem

Mamlouk from Booz Allen Hamilton, provided valuable insights that contributed substantially to

the technical content of this document. Moreover, we gratefully acknowledge and appreciate the

many comments from the public and private sectors whose thoughtful and constructive

comments improved the quality and utility of this publication.

SP 800-30 Page iii
TABLE OF CONTENTS

1. INTRODUCTION

1.1 Authority

1.2 Purpose

1.3 Objective

1.4 Target Audience

1.5 Related References

1.6 Guide Structure

2. RISK MANAGEMENT OVERVIEW

2.1 Importance of Risk Management

2.2 Integration of Risk Management into SDLC .. 2.3 Key Roles

3. RISK ASSESSMENT

3.1 Step 1 : System Characterization

3.1.1 System-Related Information

3.1.2 Information-Gathering Techniques

3.2 Step 2: Threat Identification

3.2.1 Threat-Source Identification

3.2.2 Motivation and Threat Actions

3.3 Step 3: Vulnerability Identification

3.3.1 Vulnerability Sources

3.3.2 System Security Testing , 3.3.3 Development ofSecurity Requirements Checklist. 3.4 Step 4: Control Analysis

3.4.1 Control Methods

3.4.2 Control Categories

3.4.3 Control Analysis Technique

3.5 Step 5 : Likelihood Determination

3.6 Step 6: Impact Analysis

3.7 Step?: Risk Determination

3.7.1 Risk-Level Matrix

3.7.2 Description ofRisk Level

3.8 Step 8: Control Recommendations

3.9 Step 9: Results Documentation

4. RISK MITIGATION

4.1 Risk Mitigation Options

4.2 Risk Mitigation Strategy

4.3 Approach for Control Implementation , 4.4 Control Categories

4.4.1 Technical Security Controls

4.4.2 Management Security Controls

4.4.3 Operational Security Controls

4.5 Cost-Benefit Analysis

4.6 Residual Risk

5. EVALUATION AND ASSESSMENT

5.1 Ciood Security Practice

5.2 Keys for Success

Appendix A—Sample Interview Questions AAppendix B—Sample Risk Assessment Report Outline BSP 800-30 Page
Appendix C—Sample Implementation Safeguard Plan Summary Table C-1

Appendix D—Acronyms D-1

Appendix E—Glossary E-1

Appendix F—References F

LIST OF FIGURES

Figure 3-1 Risk Assessment Methodology Flowchart 9

Figure 4-1 Risk Mitigation Action Points 28

Figure 4-2 Risk Mitigation Methodology Flowchart 3

Figure 4-3 Technical Security Controls 33

Figure 4-4 Control Implementation and Residual Risk 40

LIST OF TABLES

Table 2-1 Integration of Risk Management to the SDLC 5

Table 3-1 Human Threats: Threat-Source, Motivation, and Threat Actions 14

Table 3-2 Vulnerability/Threat Pairs 15

Table 3-3 Security Criteria 18

Table 3-4 Likelihood Definitions 21

Table 3-5 Magnitude of Impact Definitions 23

Table 3-6 Risk-Level Matrix 25

Table 3-7 Risk Scale and Necessary Actions 25

SP 800-30 Page v

I

!

' 1. INTRODUCTION

Every organization has a mission. In this digital era, as organizations use automated information

technology (IT) systems^ to process their information for better support of their missions, risk

management plays a critical role in protecting an organization's information assets, and therefore

its mission, from IT-related risk.

An effective risk management process is an important component of a successful IT security

program. The principal goal of an organization's risk management process should be to protect

the organization and its ability to perform their mission, not just its IT assets. Therefore, the risk

management process should not be treated primarily as a technical function carried out by the IT

experts who operate and manage the IT system, but as an essential management function of the

organization.

1.1 AUTHORITY

This document has been developed by NIST in furtherance of its statutory responsibilities under

the Computer Security Act of 1987 and the Information Technology Management Reform Act of

1996 (specifically 15 United States Code (U.S.C.) 278 g-3 (a)(5)). This is not a guideline within

the meaning of 15 U.S.C 278 g-3 (a)(3).

These guidelines are for use by Federal organizations which process sensitive information.

They are consistent with the requirements of 0MB Circular A-130, Appendix HI.

The guidelines herein are not mandatory and binding standards. This document may be used by

non-governmental organizations on a voluntary basis. It is not subject to copyright.

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

mandatory and binding upon Federal agencies by the Secretary of Commerce under his statutory

authority. Nor should these guidelines be interpreted as altering or superseding the existing

authorities of the Secretary of Commerce, the Director of the Office of Management and Budget,

or any other Federal official.

1.2 PURPOSE

Risk is the net negative impact of the exercise of a vulnerability, considering both the probability

and the impact of occurrence. Risk management is the process of identifying risk, assessing risk,

and taking steps to reduce risk to an acceptable level. This guide provides a foundation for the

development of an effective risk management program, containing both the definitions and the

practical guidance necessary for assessing and mitigating risks identified within IT systems. The

ultimate goal is to help organizations to better manage IT-related mission risks.

1 The term "IT system" refers to a general support system (e.g., mainframe computer, mid-range computer, local area network, agencywide backbone) or a major application that can run on a general support system and whose

use of information resources satisfies a specific set of user requirements.

SP 800-30 Page 1
In addition, this guide provides information on the selection of cost-effective security controls.^

These controls can be used to mitigate risk for the better protection of mission-critical

information and the IT systems that process, store, and carry this information.

Organizations may choose to expand or abbreviate the comprehensive processes and steps

suggested in this guide and tailor them to their environment in managing IT-related mission

risks.

1.3 OBJECTIVE

The objective of performing risk management is to enable the organization to accomplish its

mission(s) (1) by better securing the IT systems that store, process, or transmit organizational

information; (2) by enabling management to make well-informed risk management decisions to

justify the expenditures that are part of an IT budget; and (3) by assisting management in

authorizing (or accrediting) the IT systems-^ on the basis of the supporting documentation

resulting from the performance of risk management.

1.4 TARGET AUDIENCE

This guide provides a common foundation for experienced and inexperienced, technical, and

non-technical personnel who support or use the risk management process for their IT systems.

These personnel include

• Senior management, the mission owners, who make decisions about the IT security

budget.

• Federal Chief Information Officers, who ensure the implementation of risk

management for agency IT systems and the security provided for these IT systems

• The Designated Approving Authority (DAA), who is responsible for the final

decision on whether to allow operation of an IT system

• The IT security program manager, who implements the security program

• Information system security officers (ISSO), who are responsible for IT security

• IT system owners of system software and/or hardware used to support IT functions.

• Information owners of data stored, processed, and transmitted by the IT systems

• Business or functional managers, who are responsible for the IT procurement process

• Technical support personnel (e.g., network, system, application, and database

administrators; computer specialists; data security analysts), who manage and

administer security for the IT systems

• IT system and application programmers, who develop and maintain code that could

affect system and data integrity

The terms "safeguards" and "controls" refer to risk-reducing measures; these terms are used interchangeably in

this guidance document.

Office of Management and Budget's November 2000 Circular A-130, the Computer Security Act of 1987, and the

Government Information Security Reform Act of October 2000 require that an IT system be authorized prior to operation and reauthorized at least every 3 years thereafter.

SP 800-30 Page 2
• IT quality assurance personnel, who test and ensure the integrity of the IT systems

and data

• Information system auditors, who audit IT systems

• IT consultants, who support clients in risk management.

1.5 RELATED REFERENCES

This guide is based on the general concepts presented in National Institute of Standards and

Technology (NIST) Special Publication (SP) 800-27, Engineering Principles for IT Security,

along with the principles and practices in NIST SP 800-14, Generally Accepted Principles and

Practices for Securing Information Technology Systems. In addition, it is consistent with the

policies presented in Office of Management and Budget (0MB) Circular A-130, Appendix III,

"Security of Federal Automated Information Resources"; the Computer Security Act (CSA) of

1987; and the Government Information Security Reform Act of October 2000.

1.6 GUIDE STRUCTURE

The remaining sections of this guide discuss the following:

• Section 2 provides an overview of risk management, how it fits into the system

development life cycle (SDLC), and the roles of individuals who support and use this

process.

• Section 3 describes the risk assessment methodology and the nine primary steps in

conducting a risk assessment of an IT system.

• Section 4 describes the risk mitigation process, including risk mitigation options and

strategy, approach for control implementation, control categories, cost-benefit

analysis, and residual risk.

• Section 5 discusses the good practice and need for an ongoing risk evaluation and

assessment and the factors that will lead to a successful risk management program.

This guide also contains six appendixes. Appendix A provides sample interview questions.

Appendix B provides a sample outline for use in documenting risk assessment results. Appendix

C contains a sample table for the safeguard implementation plan. Appendix D provides a list of

the acronyms used in this document. Appendix E contains a glossary of terms used frequently in

this guide. Appendix F lists references.

SP 800-30 Page 3
2. RISK MANAGEMENT OVERVIEW

This guide describes the risk management methodology, how it fits into each phase of the SDLC,

and how the risk management process is tied to the process of system authorization (or

accreditation).

2.1 IMPORTANCE OF RISK MANAGEMENT

Risk management encompasses three processes: risk assessment, risk mitigation, and evaluation

and assessment. Section 3 of this guide describes the risk assessment process, which includes

identification and evaluation of risks and risk impacts, and recommendation of risk-reducing

measures. Section 4 describes risk mitigation, which refers to prioritizing, implementing, and

maintaining the appropriate risk-reducing measures recommended from the risk assessment

process. Section 5 discusses the continual evaluation process and keys for implementing a successful risk management program. The DAA or system authorizing official is responsible for

determining whether the remaining risk is at an acceptable level or whether additional security

controls should be implemented to further reduce or eliminate the residual risk before

authorizing (or accrediting) the IT system for operation.

Risk management is the process that allows IT managers to balance the operational and

economic costs of protective measures and achieve gains in mission capability by protecting the

IT systems and data that support their organizations' missions. This process is not unique to the

IT environment; indeed it pervades decision-making in all areas of our daily lives. Take the case of home security, for example. Many people decide to have home security systems installed and

pay a monthly fee to a service provider to have these systems monitored for the better protection

of their property. Presumably, the homeowners have weighed the cost of system installation and

monitoring against the value of their household goods and their family's safety, a fundamental

"mission" need.

The head of an organizational unit must ensure that the organization has the capabilities needed

to accomplish its mission. These mission owners must determine the security capabilities that

their IT systems must have to provide the desired level of mission support in the face of realworld threats. Most organizations have tight budgets for IT security; therefore, IT security

spending must be reviewed as thoroughly as other management decisions. A well-structured risk

management methodology, when used effectively, can help management identify appropriate

controls for providing the mission-essential security capabilities.

2.2 INTEGRATION OF RISK MANAGEMENT INTO SDLC

Minimizing negative impact on an organization and need for sound basis in decision making are the fundamental reasons organizations implement a risk management process for their IT

systems. Effective risk management must be totally integrated into the SDLC. An IT system's

SDLC has five phases: initiation, development or acquisition, implementation, operation or maintenance, and disposal. In some cases, an IT system may occupy several of these phases at the same time. However, the risk management methodology is the same regardless of the SDLC

phase for which the assessment is being conducted. Risk management is an iterative process that

can be performed during each major phase of the SDLC. Table 2-1 describes the characteristics

SP 800-30 Page 4
of each SDLC phase and indicates how risk management can be performed in support of each

phase.

Table 2-1 Integration of Risk Management into the SDLC

SDLC Phases Phase Characteristics Support from Risl(

l\/lanagement Activities

Phase 1 —Initiation The need for an IT system is expressed and the purpose and

scope of the IT system is documented

• Identified risks are used to support the development of the

system requirements, including

security requirements, and a

security concept of operations

(strategy)

Phase 2—Development or

Acquisition

The IT system is designed,

purchased, programmed,

developed, or otherwise

constructed

• The risks identified during this

phase can be used to support

the security analyses of the IT system that may lead to

architecture and design tradeoffs during system

development

Phase 3—Implementation The system security features

should be configured, enabled,

tested, and verified

• The risk management process

supports the assessment of the

system implementation against

its requirements and within its modeled operational

environment. Decisions

regarding risks identified must

be made prior to system

operation

Phase 4—Operation or Maintenance

The system performs its functions. Typically the system is being modified on an ongoing

basis through the addition of

hardware and software and by

changes to organizational

processes, policies, and

procedures

• Risk management activities are performed for periodic system

reauthorization (or

reaccreditation) or whenever

major changes are made to an

IT system in its operational,

production environment (e.g.,

new system interfaces)

Phase 5—Disposal This phase may involve the

disposition of information,

hardware, and software.

Activities may include moving,

archiving, discarding, or destroying information and

sanitizing the hardware and

software

• Risk management activities are performed for system

components that will be

disposed of or replaced to

ensure that the hardware and

software are properly disposed

of, that residual data is appropriately handled, and that

system migration is conducted

in a secure and systematic

manner

SP 800-30 Page 5
2.3 KEY ROLES

Risk management is a management responsibility. This section describes the key roles of the

personnel who should support and participate in the risk management process.

• Senior Management. Senior management, under the standard of due care and

ultimate responsibility for mission accomplishment, must ensure that the necessary

resources are effectively applied to develop the capabilities needed to accomplish the

mission. They must also assess and incorporate results of the risk assessment activity

into the decision making process. An effective risk management program that assesses and mitigates IT-related mission risks requires the support and involvement

of senior management.

• Chief Information Officer (CIO). The CIO is responsible for the agency's IT

planning, budgeting, and performance including its information security components.

Decisions made in these areas should be based on an effective risk management

program.

• System and Information Owners. The system and information owners are responsible for ensuring that proper controls are in place to address integrity,

confidentiality, and availability of the IT systems and data they own. Typically the

system and information owners are responsible for changes to their IT systems. Thus,

they usually have to approve and sign off on changes to their IT systems (e.g., system

enhancement, major changes to the software and hardware). The system and

information owners must therefore understand their role in the risk management

process and fully support this process.

• Business and Functional Managers. The managers responsible for business

operations and IT procurement process must take an active role in the risk

management process. These managers are the individuals with the authority and

responsibility for making the trade-off decisions essential to mission accomplishment.

Their involvement in the risk management process enables the achievement of proper

security for the IT systems, which, if managed properly, will provide mission

effectiveness with a minimal expenditure of resources.

• ISSO. IT security program managers and computer security officers are responsible

for their organizations' security programs, including risk management. Therefore,

they play a leading role in introducing an appropriate, structured methodology to help

identify, evaluate, and minimize risks to the IT systems that support their

organizations' missions. ISSOs also act as major consultants in support of senior

management to ensure that this activity takes place on an ongoing basis.

• IT Security Practitioners. IT security practitioners (e.g., network, system,

application, and database administrators; computer specialists; security analysts;

security consultants) are responsible for proper implementation of security

requirements in their IT systems. As changes occur in the existing IT system

environment (e.g., expansion in network connectivity, changes to the existing

infrastructure and organizational policies, introduction of new technologies), the IT

security practitioners must support or use the risk management process to identify and

assess new potential risks and implement new security controls as needed to

safeguard their IT systems.

SP 800-30 Page 6
• Security Awareness Trainers (Security/Subject Matter Professionals). The

organization's personnel are the users of the IT systems. Use of the IT systems and

data according to an organization's policies, guidelines, and rules of behavior is

critical to mitigating risk and protecting the organization's IT resources. To minimize

risk to the IT systems, it is essential that system and application users be provided

with security awareness training. Therefore, the IT security trainers or

security/subject matter professionals must understand the risk management process so

that they can develop appropriate training materials and incorporate risk assessment

into training programs to educate the end users.

SP 800-30 Page 7
3. RISK ASSESSMENT

Risk assessment is the first process in the risk management methodology. Organizations use risk

assessment to determine the extent of the potential threat and the risk associated with an IT

system throughout its SDLC. The output of this process helps to identify appropriate controls for

reducing or eliminating risk during the risk mitigation process, as discussed in Section 4.

Risk is a function of the likelihood of a given threat-source's exercising a particular potential

vulnerability, and the resulting impact of that adverse event on the organization.

To determine the likelihood of a future adverse event, threats to an IT system must be analyzed

in conjunction with the potential vulnerabilities and the controls in place for the IT system.

Impact refers to the magnitude of harm that could be caused by a threat's exercise of a

vulnerability. The level of impact is governed by the potential mission impacts and in turn

produces a relative value for the IT assets and resources affected (e.g., the criticality and

sensitivity of the IT system components and data). The risk assessment methodology

encompasses nine primary steps, which are described in Sections 3.1 through 3.9

• Step 1—System Characterization (Section 3.1)

• Step 2—^Threat Identification (Section 3.2)

• Step 3—^Vulnerability Identification (Section 3.3)

• Step A—Control Analysis (Section 3.4)

• Step 5—Likelihood Determination (Section 3.5)

• Step 6—Impact Analysis (Section 3.6)

• Step 7—Risk Determination (Section 3.7)

• Step 8—Control Recommendations (Section 3.8)

• Step 9—Results Documentation (Section 3.9).

Steps 2, 3, 4, and 6 can be conducted in parallel after Step 1 has been completed. Figure 3-1

depicts these steps and the inputs to and outputs from each step.

SP 800-30 Pages
Input Risk Assessment Activities Output

• Hardware

• Software

• System interfaces

• Data and information

• People

^» System mission ,

' History of system attack

' Data from intelligence

agencies, NIPC, OIG. FedCIRC, mass media.

• Reports from prior risk assessments

• Any audit comments

• Security requirements

• Security test results

> Current controls

' Planned controls

• Threat-source motivation

• Threat capacity

• Nahire of vulnerability

• Current controls

• Mission impact analysis

• Asset criticality assessment

• Data criticality

• Data sensitivity

' Likelihood of threat exploitation

' Magnitude of impact

' Adequacy of plaimed or

current controls

Step 1. System Characterization

I

Step 2. Threat Identification

I

Step 3.

->| Vulnerability Identification

I

Step 4. Control Analysis

I

I

Step 6. Impact Analysis

• Loss of Integrity

• Loss of Availability

• Loss of Confidentiality

I

Step 7. Risk Determination

Step 9. Results Documentation

• System Boundary

• System Functions

• System and Data

Criticality

• System and Data

Sensitivity

Threat Statement

List of Potential

Vulnerabilities

List of Current and

Planned Controls

Step 5. — 1 Likelihood Determination

Likelihood Rating

Impact Rating

Risks and

Associated Risk

Levels

r Step 8. — Recommended

Control Recommendations Controls

Risk Assessment

Report

Figure 3-1. Risk Assessment Methodology Flowchart

SP 800-30 Page 9
3.1 STEPl: SYSTEM CHARACTERIZATION

In assessing risks for an IT system, the first step is to define the scope of the effort. In this step,

the boundaries of the IT system are identified, along with the resources and the information that

constitute the system. Characterizing an IT system establishes the scope of the risk assessment

effort, delineates the operational authorization (or accreditation) boundaries, and provides

information (e.g., hardware, software, system connectivity, and responsible division or support

personnel) essential to defining the risk.

Section 3.1.1 describes the system-related information used to characterize an IT system and its

operational environment. Section 3.1.2 suggests the information-gathering techniques that can

be used to solicit information relevant to the IT system processing environment.

The methodology described in this document can be applied to assessments of single or multiple,

interrelated systems. In the latter case, it is important that the domain of interest and all interfaces

and dependencies be well defined prior to applying the methodology.

3.1.1 System-Related Information

Identifying risk for an IT system requires a keen understanding of the system's processing

environment. The person or persons who conduct the risk assessment must therefore first collect

system-related information, which is usually classified as follows:

• Hardware

• Software

• System interfaces (e.g., internal and external connectivity)

• Data and information

• Persons who support and use the IT system

• System mission (e.g., the processes performed by the IT system)

• System and data criticality (e.g., the system's value or importance to an organization)

• System and data sensitivity.^

Additional information related to the operational environmental of the IT system and its data

includes, but is not limited to, the following:

• The functional requirements of the IT system

• Users of the system (e.g., system users who provide technical support to the IT

system; application users who use the IT system to perform business functions)

• System security policies governing the IT system (organizational policies, federal

requirements, laws, industry practices)

• System security architecture

^ The level of protection required to maintain system and data integrity, confidentiality, and availability.

SP 800-30 Page 10
• Current network topology (e.g., network diagram)

• Information storage protection that safeguards system and data availability, integrity,

and confidentiality

• Flow of information pertaining to the IT system (e.g., system interfaces, system input

and output flowchart)

• Technical controls used for the IT system (e.g., built-in or add-on security product

that supports identification and authentication, discretionary or mandatory access

control, audit, residual information protection, encryption methods)

• Management controls used for the IT system (e.g., rules of behavior, security

planning)

• Operational controls used for the IT system (e.g., personnel security, backup,

contingency, and resumption and recovery operations; system maintenance; off-site

storage; user account establishment and deletion procedures; controls for segregation

of user functions, such as privileged user access versus standard user access)

• Physical security environment of the IT system (e.g., facility security, data center

policies)

• Environmental security implemented for the IT system processing environment (e.g.,

controls for humidity, water, power, pollution, temperature, and chemicals).

For a system that is in the initiation or design phase, system information can be derived from the

design or requirements document. For an IT system under development, it is necessary to define

key security rules and attributes planned for the future IT system. System design documents and

the system security plan can provide useful information about the security of an IT system that is

in development.

For an operational IT system, data is collected about the IT system in its production

environment, including data on system configuration, connectivity, and documented and

undocumented procedures and practices. Therefore, the system description can be based on the

security provided by the underlying infrastructure or on future security plans for the IT system.

3.1.2 Information-Gathering Techniques

Any, or a combination, of the following techniques can be used in gathering information relevant

to the IT system within its operational boundary:

• Questionnaire. To collect relevant information, risk assessment personnel can

develop a questionnaire concerning the management and operational controls planned

or used for the IT system. This questionnaire should be distributed to the applicable

technical and nontechnical management personnel who are designing or supporting

the IT system. The questionnaire could also be used during on-site visits and

interviews.

• On-site Interviews. Interviews with IT system support and management personnel

can enable risk assessment personnel to collect useful information about the IT

system (e.g., how the system is operated and managed). On-site visits also allow risk

SP 800-30 Page 1
assessment personnel to observe and gather information about the physical,

environmental, and operational security of the IT system. Appendix A contains

sample interview questions asked during interviews with site personnel to achieve a

better understanding of the operational characteristics of an organization. For

systems still in the design phase, on-site visit would be face-to-face data gathering

exercises and could provide the opportunity to evaluate the physical environment in

which the IT system will operate.

• Document Review. Policy documents (e.g., legislative documentation, directives),

system documentation (e.g., system user guide, system administrative manual,

system design and requirement document, acquisition document), and security-related

documentation (e.g., previous audit report, risk assessment report, system test results,

system security plan^, security policies) can provide good information about the

security controls used by and planned for the IT system. An organization's mission

impact analysis or asset criticality assessment provides information regarding system

and data criticality and sensitivity.

• Use of Automated Scanning Tool. Proactive technical methods can be used to

collect system information efficiently. For example, a network mapping tool can

identify the services that run on a large group of hosts and provide a quick way of

building individual profiles of the target IT system(s).

Information gathering can be conducted throughout the risk assessment process, from Step 1 (System Characterization) through Step 9 (Results Documentation).

Outputfrom Step 1—Characterization ofthe IT system assessed, a good picture ofthe IT

system environment, and delineation ofsystem boundary

3.2 STEP 2: THREAT IDENTIFICATION

A threat is the potential for a particular threat-source to successfully exercise a particular

vulnerability. A vulnerability is a weakness that can

be accidentally triggered or intentionally exploited. A

threat-source does not present a risk when there is no

vulnerability that can be exercised. In determining the

likelihood of a threat (Section 3.5), one must consider

threat-sources, potential vulnerabilities (Section 3.3),

and existing controls (Section 3.4).

Threat: The potential for a threatsource to exercise (accidentally trigger or intentionally exploit) a specific

vulnerability.

3.2.1 Threat-Source Identification

The goal of this step is to identify the potential

threat-sources and compile a threat statement

listing potential threat-sources that are applicable

to the IT system being evaluated.

Threat-Source: Either (1) intent and method

targeted at the intentional exploitation of a

vulnerability or (2) a situation and method

that may accidentally trigger a vulnerability.

^ During the initial phase, a risk assessment could be used to develop the initial system security plan.

SP 800-30 Page 12
A threat-source is defined as any

circumstance or event with the

potential to cause harm to an IT

system. The common threatsources can be natural, human, or environmental.

In assessing threat-sources, it is

important to consider all potential

threat-sources that could cause

harm to an IT system and its

processing environment. For

example, although the threat

statement for an IT system

located in a desert may not

include "natural flood" because

of the low likelihood of such an event's occurring, environmental threats such as a bursting pipe

can quickly flood a computer room and cause damage to an organization's IT assets and

resources. Humans can be threat-sources through intentional acts, such as deliberate attacks by

malicious persons or disgruntled employees, or unintentional acts, such as negligence and errors. A deliberate attack can be either (1) a malicious attempt to gain unauthorized access to an IT

system (e.g., via password guessing) in order to compromise system and data integrity,

availability, or confidentiality or (2) a benign, but nonetheless purposeful, attempt to circumvent

system security. One example of the latter type of deliberate attack is a programmer's writing a Trojan horse program to bypass system security in order to "get the job done."

3.2.2 Motivation and Tlireat Actions

Motivation and the resources for carrying out an attack make humans potentially dangerous

threat-sources. Table 3-1 presents an overview of many of today's common human threats, their

possible motivations, and the methods or threat actions by which they might carry out an attack.

This information will be useful to organizations studying their human threat environments and

customizing their human threat statements. In addition, reviews of the history of system breakins; security violation reports; incident reports; and interviews with the system administrators,

help desk personnel, and user community during information gathering will help identify human

threat-sources that have the potential to harm an IT system and its data and that may be a concern

where a vulnerability exists.

Common Threat-Sources

Natural Threats—^Floods, earthquakes, tornadoes,

landslides, avalanches, electrical storms, and other such

events.

« Human Threats—^Events that are either enabled by or

caused by human beings, such as unintentional acts

(inadvertent data entry) or deliberate actions (network

based attacks, malicious software upload, unauthorized

access to confidential information),

Environmental Threats—Long-term power failure,

pollution, chemicals, liquid leakage.

SP800-30 Page 13
Table 3-1. Human Threats: Threat-Source, Motivation, and Threat Actions

Threat-Source Motivation Threat Actions

Hacker, cracker

Challenge

Ego

Rebellion

• Hacking

• Social engineering

• System intrusion, break-ins

• Unauthorized system access

Computer criminal

Destruction of information

lllonf)! information Hicolociiro

Monetary gain

Unauthorized data alteration

• Computer crime (e.g., cyber

stalking)

• Fraudulent act (e.g., replay,

impersonation, interception)

• Information bribery

• Spoofing

• System intrusion

Terrorist

Blackmail

Destruction

Exploitation

Revenge

• Bomb/Terrorism

• Information warfare

• System attack (e.g., distributed

denial of service)

• System penetration

• System tampering

Industrial espionage

(companies, foreign

novprnmpnt^ UWUI 1 II 1 1^1 IIO, nthpr V/il Iwl government interests)

Competitive advantage

Economic espionage

• Economic exploitation

• Information theft

• Intrusion on personal privacy

• Social engineering

• System penetration

• Unauthorized system access

(access to classified, proprietary,

and/or technology-related

information)

Insiders (poorly trained,

disgruntled, malicious,

negligent, dishonest, or terminated employees)

Curiosity

Ego

Intelligence

Monetary gain

Revenge

Unintentional errors and

omissions (e.g., data entry

error, programming error)

• Assault on an employee

• Blackmail

• Browsing of proprietary

information

• Computer abuse

• Fraud and theft

• Information bribery

• Input of falsified, corrupted data

• Interception

• Malicious code (e.g., virus, logic

bomb, Trojan horse)

• Sale of personal information

• System bugs

• System intrusion

• System sabotage

• Unauthorized system access

An estimate of the motivation, resources, and capabilities that may be required to carry out a

successful attack should be developed after the potential threat-sources have been identified, in

order to determine the likelihood of a threat's exercising a system vulnerability, as described in

Section 3.5.

SP 800-30 Page 14

j

i

I
The threat statement, or the list of potential threat-sources, should be tailored to the individual

organization and its processing environment (e.g., end-user computing habits). In general,

information on natural threats (e.g., floods, earthquakes, storms) should be readily available.

Known threats have been identified by many government and private sector organizations.

Intrusion detection tools also are becoming more prevalent, and government and industry

organizations continually collect data on security events, thereby improving the ability to

realistically assess threats. Sources of information include, but are not limited to, the following:

• Intelligence agencies (for example, the Federal Bureau of Investigation's National

Infrastructure Protection Center)

• Federal Computer Incident Response Center (FedCIRC)

• Mass media, particularly Web-based resources such as SecurityFocus.com,

SecurityWatch.com, SecurityPortal.com, and SANS.org.

Outputfrom Step 2—A threat statement containing a list ofthreat-sources that could exploit

system vulnerabilities

3.3 STEP 3: VULNERABILITY IDENTIFICATION

The analysis of the threat to an IT system

must include an analysis of the

vulnerabilities associated with the system

environment. The goal of this step is to

develop a list of system vulnerabilities

(flaws or weaknesses) that could be

exploited by the potential threat-sources.

Table 3-2 presents examples of vulnerability/threat pairs.

Table 3-2. Vulnerability/Threat Pairs

Vulnerability Threat-Source Threat Action

Terminated employees' system

identifiers (ED) are not removed

from the system

Terminated employees Dialing into the company's

network and accessing

company proprietary data

Company firewall allows inbound

telnet, and guest YD is enabled on

XYZ server

Unauthorized users (e.g.,

hackers, terminated

employees, computer

criminals, terrorists)

Using telnet to XYZ server and browsing system files

with the guest ID

The vendor has identified flaws in

the security design of the system;

however, new patches have not

been applied to the system

Unauthorized users (e.g.,

hackers, disgruntled

employees, computer

criminals, terrorists)

Obtaining unauthorized

access to sensitive system

files based on known

system vulnerabilities

Vulnerability: A flaw or weakness in system

security procedures, design, implementation, or

internal controls that could be exercised

(accidentally triggered or intentionally exploited)

and result in a security breach or a violation of the

system's security poUcy.

SP 800-30 Page 15
Vulnerability Threat-Source Threat Action

Data center uses water sprinklers

to suppress fire; tarpaulins to

protect hardware and equipment

from water damage are not in

place

Fire, negligent persons Water sprinklers being

turned on in the data center

Recommended methods for identifying system vulnerabilities are the use of vulnerability

sources, the performance of system security testing, and the development of a security

requirements checklist.

It should be noted that the types of vulnerabilities that will exist, and the methodology needed to

determine whether the vulnerabilities are present, will usually vary depending on the nature of

the IT system and the phase it is in, in the SDLC:

• If the IT system has not yet been designed, the search for vulnerabilities should focus

on the organization's security policies, planned security procedures, and system

requirement definitions, and the vendors' or developers' security product analyses

(e.g., white papers).

• If the IT system is being implemented, the identification of vulnerabilities should be

expanded to include more specific information, such as the planned security features

described in the security design documentation and the results of system certification

test and evaluation.

• If the IT system is operational, the process of identifying vulnerabilities should

include an analysis of the IT system security features and the security controls,

technical and procedural, used to protect the system.

3.3.1 Vulnerability Sources

The technical and nontechnical vulnerabilities associated with an IT system's processing

environment can be identified via the information-gathering techniques described in Section

3.1.2. A review of other industry sources (e.g., vendor Web pages that identify system bugs and

flaws) will be useful in preparing for the interviews and in developing effective questionnaires to

identify vulnerabilities that may be applicable to specific IT systems (e.g., a specific version of a

specific operating system). The Internet is another source of information on known system

vulnerabilities posted by vendors, along with hot fixes, service packs, patches, and other

remedial measures that may be applied to eliminate or mitigate vulnerabilities. Documented

vulnerability sources that should be considered in a thorough vulnerability analysis include, but

are not limited to, the following:

• Previous risk assessment documentation of the IT system assessed

• The IT system's audit reports, system anomaly reports, security review reports, and

system test and evaluation reports

• Vulnerability lists, such as the NIST I-CAT vulnerability database

(http://icat.nist.gov)

SP 800-30 Page 16
• Security advisories, such as FedCIRC and the Department of Energy's Computer

Incident Advisory Capability bulletins

• Vendor advisories

• Commercial computer incident/emergency response teams and post lists (e.g.,

SecurityFocus.com forum mailings)

• Information Assurance Vulnerability Alerts and bulletins for military systems

• System software security analyses.

3.3.2 System Security Testing

Proactive methods, employing system testing, can be used to identify system vulnerabilities

efficiently, depending on the criticality of the IT system and available resources (e.g., allocated

funds, available technology, persons with the expertise to conduct the test). Test methods

include

• Automated vulnerability scanning tool

• Security test and evaluation (ST&E)

• Penetration testing.*^

The automated vulnerability scanning tool is used to scan a group of hosts or a network for

known vulnerable services (e.g., system allows anonymous File Transfer Protocol [FTP],

sendmail relaying). However, it should be noted that some of the potential vulnerabilities

identified by the automated scanning tool may not represent real vulnerabilities in the context of

the system environment. For example, some of these scanning tools rate potential vulnerabilities

without considering the site's environment and requirements. Some of the "vulnerabilities"

flagged by the automated scanning software may actually not be vulnerable for a particular site

but may be configured that way because their environment requires it. Thus, this test method

may produce false positives.

ST&E is another technique that can be used in identifying IT system vulnerabilities during the

risk assessment process. It includes the development and execution of a test plan (e.g., test

script, test procedures, and expected test results). The purpose of system security testing is to

test the effectiveness of the security controls of an IT system as they have been applied in an

operational environment. The objective is to ensure that the applied controls meet the approved

security specification for the software and hardware and implement the organization's security

policy or meet industry standards.

Penetration testing can be used to complement the review of security controls and ensure that

different facets of the IT system are secured. Penetration testing, when employed in the risk

assessment process, can be used to assess an IT system's ability to withstand intentional attempts

to circumvent system security. Its objective is to test the IT system from the viewpoint of a threat-source and to identify potential failures in the IT system protection schemes.

The NIST SP draft 800-42, Network Security Testing Overview, describes the methodology for network system

testing and the use of automated tools.

SP 800-30 Page 17
The results of these types of optional security testing will help identify a system's vulnerabilities.

3.3.3 Development of Security Requirements Cliecklist

During this step, the risk assessment personnel determine whether the security requirements

stipulated for the IT system and collected during system characterization are being met by

existing or planned security controls. Typically, the system security requirements can be

presented in table form, with each requirement accompanied by an explanation of how the

system's design or implementation does or does not satisfy that security control requirement.

A security requirements checklist contains the basic security standards that can be used to

systematically evaluate and identify the vulnerabilities of the assets (personnel, hardware,

software, information), nonautomated procedures, processes, and information transfers

associated with a given IT system in the following security areas:

• Management

• Operational

• Technical.

Table 3-3 lists security criteria suggested for use in identifying an IT system's vulnerabilities in

each security area.

Table 3-3. Security Criteria

Security Area Security Criteria

Management Security

• Assignment of responsibilities

• Continuity of support

• Incident response capability

• Periodic review of security controls

• Personnel clearance and background investigations

• Risk assessment

• Security and technical training

• Separation of duties

• System authorization and reauthorization

• System or application security plan

Operational Security

• Control of air-borne contaminants (smoke, dust, chemicals)

• Controls to ensure the quality of the electrical power supply

• Data media access and disposal

• External data distribution and labeling

• Facility protection (e.g., computer room, data center, office)

• Humidity control

• Temperature control

• Workstations, laptops, and stand-alone personal computers

SP 800-30 Page 18
Security Area Security Criteria

Technical Security

• Communications (e.g., dial-in, system interconnection, routers)

• Cryptography

• Discretionary access control

• Identification and authentication

• Intrusion detection

• Object reuse

• System audit

The outcome of this process is the security requirements checklist. Sources that can be used in

compiUng such a checklist include, but are not limited to, the following government regulatory

and security directives and sources applicable to the IT system processing environment:

• CSA of 1987

• Federal Information Processing Standards Publications

• OMB November 2000 Circular A- 130

• Privacy Act of 1974

• System security plan of the IT system assessed

• The organization's security policies, guidelines, and standards

• Industry practices.

The NIST SP 800-26, Security Self-Assessment Guide for Information Technology Systems,

provides an extensive questionnaire containing specific control objectives against which a system or group of interconnected systems can be tested and measured. The control objectives

are abstracted directly from long-standing requirements found in statute, policy, and guidance on

security and privacy.

The results of the checklist (or questionnaire) can be used as input for an evaluation of

compliance and noncompliance. This process identifies system, process, and procedural

weaknesses that represent potential vulnerabilities.

Outputfrom Step 3—A list ofthe system vulnerabilities (observations)"^ that could be exercised

by the potential threat-sources

3.4 STEP 4: CONTROL ANALYSIS

The goal of this step is to analyze the controls that have been implemented, or are planned for

implementation, by the organization to minimize or eliminate the likelihood (or probability) of a

threat's exercising a system vulnerability.

Because the risk assessment report is not an audit report, some sites may prefer to address the identified

vulnerabiUties as observations instead of findings in the risk assessment report.

SP 800-30 Page 19
To derive an overall likelihood rating that indicates the probability that a potential vulnerability

may be exercised within the construct of the associated threat environment (Step 5 below), the

implementation of current or planned controls must be considered. For example, a vulnerability

(e.g., system or procedural weakness) is not likely to be exercised or the likelihood is low if there

is a low level of threat-source interest or capability or if there are effective security controls that

can eliminate, or reduce the magnitude of, harm.

Sections 3.4.1 through 3.4.3, respectively, discuss control methods, control categories, and the

control analysis technique.

3.4.1 Control Methods

Security controls encompass the use of technical and nontechnical methods. Technical controls

are safeguards that are incorporated into computer hardware, software, or firmware (e.g., access

control mechanisms, identification and authentication mechanisms, encryption methods,

intrusion detection software). Nontechnical controls are management and operational controls,

such as security policies; operational procedures; and personnel, physical, and environmental

security.

3.4.2 Control Categories

The control categories for both technical and nontechnical control methods can be further

classified as either preventive or detective. These two subcategories are explained as follows:

• Preventive controls inhibit attempts to violate security policy and include such

controls as access control enforcement, encryption, and authentication.

• Detective controls warn of violations or attempted violations of security policy and

include such controls as audit trails, intrusion detection methods, and checksums.

Section 4.4 further explains these controls from the implementation standpoint. The

implementation of such controls during the risk mitigation process is the direct result of the

identification of deficiencies in current or planned controls during the risk assessment process

(e.g., controls are not in place or controls are not properly implemented).

3.4.3 Control Analysis Technique

As discussed in Section 3.3.3, development of a security requirements checklist or use of an

available checklist will be helpful in analyzing controls in an efficient and systematic manner.

The security requirements checklist can be used to validate security noncompliance as well as compliance. Therefore, it is essential to update such checklists to reflect changes in an

organization's control environment (e.g., changes in security policies, methods, and

requirements) to ensure the checklist's validity.

Outputfrom Step 4—List of current or planned controls usedfor the IT system to mitigate the

likelihood ofa vulnerability's being exercised and reduce the impact ofsuch an adverse event

SP 800-30 Page 20
3.5 STEPS: LIKELIHOOD DETERMINATION

To derive an overall likelihood rating that indicates the probability that a potential vulnerability

may be exercised within the construct of the associated threat environment, the following

governing factors must be considered:

• Threat-source motivation and capability

• Nature of the vulnerability

• Existence and effectiveness of current controls.

The likelihood that a potential vulnerability could be exercised by a given threat-source can be

described as high, medium, or low. Table 3-4 below describes these three likelihood levels.

Table 3-4. Likelihood Definitions

Likelihood Level Likelihood Definition

High The threat-source is highly motivated and sufficiently capable, and controls to

prevent the vulnerability from being exercised are ineffective.

Medium The threat-source is motivated and capable, but controls are in place that may

impede successful exercise of the vulnerability.

Low The threat-source lacks motivation or capability, or controls are in place to

prevent, or at least significantly impede, the vulnerability from being exercised.

Outputfrom Step 5—Likelihood rating (High, Medium, Low)

3.6 STEP 6: IMPACT ANALYSIS

The next major step in measuring level of risk is to determine the adverse impact resulting from

a successful threat exercise of a vulnerability. Before beginning the impact analysis, it is

necessary to obtain the following necessary information as discussed in Section 3.1.1:

• System mission (e.g., the processes performed by the IT system)

• System and data criticality (e.g., the system's value or importance to an organization)

• System and data sensitivity.

This information can be obtained from existing organizational documentation, such as the

mission impact analysis report or asset criticality assessment report. A mission impact analysis

(also known as business impact analysis [BIA] for some organizations) prioritizes the impact

levels associated with the compromise of an organization's information assets based on a

qualitative or quantitative assessment of the sensitivity and criticality of those assets. An asset

criticality assessment identifies and prioritizes the sensitive and critical organization information

assets (e.g., hardware, software, systems, services, and related technology assets) that support the

organization's critical missions.

SP 800-30 Page 21
If this documentation does not exist or such assessments for the organization's IT assets have not

been performed, the system and data sensitivity can be determined based on the level of

protection required to maintain the system and data's availability, integrity, and confidentiality.

Regardless of the method used to determine how sensitive an IT system and its data are, the

system and information owners are the ones responsible for determining the impact level for

their own system and information. Consequently, in analyzing impact, the appropriate approach

is to interview the system and information owner(s).

Therefore, the adverse impact of a security event can be described in terms of loss or degradation

of any, or a combination of any, of the following three security goals: integrity, availability, and

confidentiality. The following list provides a brief description of each security goal and the

consequence (or impact) of its not being met:

• Loss of Integrity. System and data integrity refers to the requirement that

information be protected from improper modification. Integrity is lost if unauthorized

changes are made to the data or IT system by either intentional or accidental acts. If

the loss of system or data integrity is not corrected, continued use of the contaminated

system or corrupted data could result in inaccuracy, fraud, or erroneous decisions.

Also, violation of integrity may be the first step in a successful attack against system

availability or confidentiality. For all these reasons, loss of integrity reduces the

assurance of an IT system.

• Loss of Availability. If a mission-critical IT system is unavailable to its end users,

the organization's mission may be affected. Loss of system functionality and

operational effectiveness, for example, may result in loss of productive time, thus

impeding the end users' performance of their functions in supporting the

organization's mission.

• Loss of Confidentiality. System and data confidentiality refers to the protection of

information from unauthorized disclosure. The impact of unauthorized disclosure of

confidential information can range from the jeopardizing of national security to the

disclosure of Privacy Act data. Unauthorized, unanticipated, or unintentional

disclosure could result in loss of public confidence, embarrassment, or legal action

against the organization.

Some tangible impacts can be measured quantitatively in lost revenue, the cost of repairing the

system, or the level of effort required to correct problems caused by a successful threat action.

Other impacts (e.g., loss of public confidence, loss of credibility, damage to an organization's

interest) cannot be measured in specific units but can be qualified or described in terms of high,

medium, and low impacts. Because of the generic nature of this discussion, this guide designates

and describes only the qualitative categories—high, medium, and low impact (see Table 3.5).

SP 800-30 Page 22

\
Table 3-5. Magnitude of Impact DeHnitions

Magnitude of

Impact

impact Definition

High

Exercise of tlie vulnerability (1) may result in the highly costly loss of

major tangible assets or resources; (2) may significantly violate, harm, or impede an organization's mission, reputation, or interest; or (3) may result

in human death or serious injury.

Medium Exercise of the vulnerability (1) may result in the costly loss of tangible

assets or resources; (2) may violate, harm, or impede an organization's

mission, reputation, or interest; or (3) may result in human injury.

Low Exercise of the vulnerability (1) may result in the loss of some tangible

assets or resources or (2) may noticeably affect an organization's

mission, reputation, or interest.

Quantitative versus Qualitative Assessment

In conducting the impact analysis, consideration should be given to the advantages and

disadvantages of quantitative versus qualitative assessments. The main advantage of the

qualitative impact analysis is that it prioritizes the risks and identifies areas for immediate

improvement in addressing the vulnerabilities. The disadvantage of the qualitative analysis is

that it does not provide specific quantifiable measurements of the magnitude of the impacts,

therefore making a cost-benefit analysis of any recommended controls difficult.

The major advantage of a quantitative impact analysis is that it provides a measurement of the

impacts' magnitude, which can be used in the cost-benefit analysis of recommended controls.

The disadvantage is that, depending on the numerical ranges used to express the measurement,

the meaning of the quantitative impact analysis may be unclear, requiring the result to be

interpreted in a qualitative manner. Additional factors often must be considered to determine the

magnitude of impact. These may include, but are not limited to

• An estimation of the frequency of the threat-source's exercise of the vulnerability

over a specified time period (e.g., 1 year)

• An approximate cost for each occurrence of the threat-source's exercise of the

vulnerability

• A weighted factor based on a subjective analysis of the relative impact of a specific

threat's exercising a specific vulnerability.

Outputfrom Step 6—Magnitude ofimpact (High, Medium, or Low)

SP 800-30 Page 23
3.7 STEP 7: RISK DETERMINATION

The purpose of this step is to assess the level of risk to the IT system. The determination of risk

for a particular threat/vulnerability pair can be expressed as a function of

• The likelihood of a given threat-source's attempting to exercise a given vulnerability

• The magnitude of the impact should a threat-source successfully exercise the

vulnerability

• The adequacy of planned or existing security controls for reducing or eliminating

risk.

To measure risk, a risk scale and a risk-level matrix must be developed. Section 3.7.1 presents a standard risk-level matrix; Section 3.7.2 describes the resulting risk levels.

3.7.1 Risk-Level Matrix

The final determination of mission risk is derived by multiplying the ratings assigned for threat

likelihood (e.g., probability) and threat impact. Table 3.6 below shows how the overall risk

ratings might be determined based on inputs from the threat likelihood and threat impact

categories. The matrix below is a 3 x 3 matrix of threat likelihood (High, Medium, and Low)

and threat impact (High, Medium, and Low). Depending on the site's requirements and the

granularity of risk assessment desired, some sites may use a4x4ora5x5 matrix. The latter

can include a Very Low /Very High threat likelihood and a Very Low/Very High threat impact to

generate a Very LowA^ery High risk level. A "Very High" risk level may require possible

system shutdown or stopping of all IT system integration and testing efforts.

The sample matrix in Table 3-6 shows how the overall risk levels of High, Medium, and Low are derived. The determination of these risk levels or ratings may be subjective. The rationale for

this justification can be explained in terms of the probability assigned for each threat likelihood

level and a value assigned for each impact level. For example,

• The probability assigned for each threat likelihood level is 1.0 for High, 0.5 for

Medium, 0.1 for Low

• The value assigned for each impact level is 100 for High, 50 for Medium, and 10 for

Low.

SP 800-30 Page 24
Table 3-6. Risk-Level Matrix

Impact

Threat

Likelihood

Low

(10)

Medium

(50)

Higli

(100)

High{^.0) Low Medium High

10X1.0 = 10 50 X 1 .0 = 50 100 X 1.0 = 100

Medium (0.5) Low Medium Medium

10X0.5 = 5 50 X 0.5 = 25 100X0.5 = 50

Low (0.1) Low Low Low

10X0.1 = 1 50X0.1 = 5 100X0.1 = 10

Risk Scale: High (>50 to 100); Medium (>10to 50); Low (1 to 10)^

3.7.2 Description of Risk Level

Table 3-7 describes the risk levels shown in the above matrix. This risk scale, with its ratings of

High, Medium, and Low, represents the degree or level of risk to which an IT system, facility, or procedure might be exposed if a given vulnerability were exercised. The risk scale also presents

actions that senior management, the mission owners, must take for each risk level.

Table 3-7. Risk Scale and Necessary Actions

Risk Level Risk Description and Necessary Actions

High

If an observation or finding is evaluated as a higli risk, there is a

strong need for corrective measures. An existing systenn may

continue to operate, but a corrective action plan must be put in place as soon as possible.

Medium If an observation is rated as medium risk, corrective actions are needed and a plan must be developed to incorporate these actions

within a reasonable period of time.

Low If an observation is described as low risk, the system's DAA must

determine whether corrective actions are still required or decide to

accept the risk.

Outputfrom Step 7—Risk level (High, Medium, Low)

If the level indicated on certain items is so low as to be deemed to be "negligible" or non significant (value is <1 on risk scale of 1 to 100), one may wish to hold these aside in a separate bucket in lieu of forwarding for

management action. This will make sure that they are not overlooked when conducting the next periodic risk

assessment. It also establishes a complete record of all risks identified in the analysis. These risks may move to a new risk level on a reassessment due to a change in threat likelihood and/or impact and that is why it is critical that their identification not be lost in the exercise.

SP 800-30 Page 25
3.8 STEPS: CONTROL RECOMMENDATIONS

During this step of the process, controls that could mitigate or eliminate the identified risks, as appropriate to the organization's operations, are provided. The goal of the recommended

controls is to reduce the level of risk to the IT system and its data to an acceptable level. The

following factors should be considered in recommending controls and alternative solutions to

minimize or eliminate identified risks:

• Effectiveness of recommended options (e.g., system compatibility)

• Legislation and regulation

• Organizational policy

• Operational impact

• Safety and reliability.

The control recommendations are the results of the risk assessment process and provide input to

the risk mitigation process, during which the recommended procedural and technical security

controls are evaluated, prioritized, and implemented.

It should be noted that not all possible recommended controls can be implemented to reduce loss.

To determine which ones are required and appropriate for a specific organization, a cost-benefit

analysis, as discussed in Section 4.6, should be conducted for the proposed recommended

controls, to demonstrate that the costs of implementing the controls can be justified by the

reduction in the level of risk. In addition, the operational impact (e.g., effect on system

performance) and feasibility (e.g., technical requirements, user acceptance) of introducing the

recommended option should be evaluated carefully during the risk mitigation process.

Outputfrom Step 8—Recommendation of control(s) and alternative solutions to mitigate risk

3.9 STEP 9: RESULTS DOCUMENTATION

Once the risk assessment has been completed (threat-sources and vulnerabilities identified, risks

assessed, and recommended controls provided), the results should be documented in an official

report or briefing.

A risk assessment report is a management report that helps senior management, the mission

owners, make decisions on policy, procedural, budget, and system operational and management

changes. Unlike an audit or investigation report, which looks for wrongdoing, a risk assessment

report should not be presented in an accusatory manner but as a systematic and analytical

approach to assessing risk so that senior management will understand the risks and allocate resources to reduce and correct potential losses. For this reason, some people prefer to address

the threat/vulnerability pairs as observations instead of findings in the risk assessment report.

Appendix B provides a suggested outline for the risk assessment report.

Outputfrom Step 9—Risk assessment report that describes the threats and vulnerabilities,

measures the risk, and provides recommendations for control implementation

SP 800-30 Page 26 I
4. RISK MITIGATION

Risk mitigation, the second process of risk management, involves prioritizing, evaluating, and

implementing the appropriate risk-reducing controls recommended from the risk assessment

process.

Because the elimination of all risk is usually impractical or close to impossible, it is the

responsibility of senior management and functional and business managers to use the least-cost

approach and implement the most appropriate controls to decrease mission risk to an acceptable

level, with minimal adverse impact on the organization's resources and mission.

This section describes risk mitigation options (Section 4.1), the risk mitigation strategy (Section

4.2), an approach for control implementation (Section 4.3), control categories (Section 4.4), the

cost-benefit analysis used to justify the implementation of the recommended controls (Section

4.5), and residual risk (Section 4.6).

4.1 RISK MITIGATION OPTIONS

Risk mitigation is a systematic methodology used by senior management to reduce mission risk.

Risk mitigation can be achieved through any of the following risk mitigation options:

• Risk Assumption. To accept the potential risk and continue operating the IT system

or to implement controls to lower the risk to an acceptable level

• Risk Avoidance. To avoid the risk by eliminating the risk cause and/or consequence

(e.g., forgo certain functions of the system or shut down the system when risks are

identified)

• Risk Limitation. To limit the risk by implementing controls that minimize the

adverse impact of a threat's exercising a vulnerability (e.g., use of supporting,

preventive, detective controls)

• Risk Planning. To manage risk by developing a risk mitigation plan that prioritizes,

implements, and maintains controls

• Research and Acknowledgment. To lower the risk of loss by acknowledging the

vulnerability or flaw and researching controls to correct the vulnerability

• Risk Transference. To transfer the risk by using other options to compensate for the

loss, such as purchasing insurance.

The goals and mission of an organization should be considered in selecting any of these risk

mitigation options. It may not be practical to address all identified risks, so priority should be

given to the threat and vulnerability pairs that have the potential to cause significant mission

impact or harm. Also, in safeguarding an organization's mission and its IT systems, because of

each organization's unique environment and objectives, the option used to mitigate the risk and

the methods used to implement controls may vary. The "best of breed" approach is to use

appropriate technologies from among the various vendor security products, along with the

appropriate risk mitigation option and nontechnical, administrative measures.

SP 800-30 Page 27
4.2 RISK MITIGATION STRATEGY

Senior management, the mission owners, knowing the potential risks and recommended controls,

may ask, "When and under what circumstances should I take action? When shall I implement

these controls to mitigate the risk and protect our organization?"

The risk mitigation chart in Figure 4-1 addresses these questions. Appropriate points for

implementation of control actions are indicated in this figure by the word YES.

1

&

Unacceptable

Risk 3

Figure 4-1. Risk Mitigation Action Points

This strategy is further articulated in the following rules of thumb, which provide guidance on

actions to mitigate risks from intentional human threats:

• When vulnerability (or flaw, weakness) exists — implement assurance techniques

to reduce the likelihood of a vulnerability's being exercised.

• When a vulnerability can be exercised — apply layered protections, architectural

designs, and administrative controls to minimize the risk of or prevent this occurrence.

• When the attacker's cost is less than the potential gain -> apply protections to

decrease an attacker's motivation by increasing the attacker's cost (e.g., use of system

controls such as limiting what a system user can access and do can significantly

reduce an attacker's gain).

• When loss is too great — apply design principles, architectural designs, and

technical and nontechnical protections to limit the extent of the attack, thereby

reducing the potential for loss.

The strategy outlined above, with the exception of the third list item ("When the attacker's cost

is less than the potential gain"), also applies to the mitigation of risks arising from environmental

SP 800-30 Page 28
or unintentional human threats (e.g., system or user errors). (Because there is no "attacker," no

motivation or gain is involved.)

4.3 APPROACH FOR CONTROL IMPLEMENTATION

When control actions must be taken, the following rule applies:

Address the greatest risks and strive for sufficient risk mitigation at the lowest cost, with

minimal impact on other mission capabilities.

The following risk mitigation methodology describes the approach to control implementation:

• Step 1—Prioritize Actions

Based on the risk levels presented in the risk assessment report, the implementation

actions are prioritized. In allocating resources, top priority should be given to risk

items with unacceptably high risk rankings (e.g., risk assigned a Very High or High

risk level). These vulnerability/threat pairs will require immediate corrective action

to protect an organization's interest and mission.

Outputfrom Step 1 —Actions rankingfrom High to Low

• Step 2—Evaluate Recommended Control Options

The controls recommended in the risk assessment process may not be the most

appropriate and feasible options for a specific organization and IT system. During

this step, the feasibility (e.g., compatibility, user acceptance) and effectiveness (e.g.,

degree of protection and level of risk mitigation) of the recommended control options

are analyzed. The objective is to select the most appropriate control option for

minimizing risk.

Outputfrom Step 2—List offeasible controls

• Step 3—Conduct Cost-Benefit Analysis

To aid management in decision making and to identify cost-effective controls, a costbenefit analysis is conducted. Section 4.5 details the objectives and method of

conducting the cost-benefit analysis.

Outputfrom Step 3—Cost-benefit analysis describing the cost and benefits of

implementing or not implementing the controls

• Step 4—Select Control

On the basis of the results of the cost-benefit analysis, management determines the

most cost-effective control(s) for reducing risk to the organization's mission. The

controls selected should combine technical, operational, and management control

elements to ensure adequate security for the IT system and the organization.

Outputfrom Step 4—Selected control(s)

SP 800-30 Page 29
• Step 5—Assign Responsibility

Appropriate persons (in-house personnel or external contracting staff) who have the

appropriate expertise and skill-sets to implement the selected control are identified,

and responsibility is assigned.

Outputfrom Step 5—List ofresponsible persons

• Step 6—Develop a Safeguard Implementation Plan

During this step, a safeguard implementation plan^ (or action plan) is developed. The

plan should, at a minimum, contain the following information:

- Risks (vulnerability/threat pairs) and associated risk levels (output from risk

assessment report) - Recommended controls (output from risk assessment report) - Prioritized actions (with priority given to items with Very High and High risk

levels) - Selected planned controls (determined on the basis of feasibility, effectiveness,

benefits to the organization, and cost) - Required resources for implementing the selected planned controls - Lists of responsible teams and staff - Start date for implementation - Target completion date for implementation - Maintenance requirements.

The safeguard implementation plan prioritizes the implementation actions and

projects the start and target completion dates. This plan will aid and expedite the risk

mitigation process. Appendix C provides a sample summary table for the safeguard

implementation plan.

Outputfrom Step 6—Safeguard implementation plan

• Step 7—^Implement Selected Control(s)

Depending on individual situations, the implemented controls may lower the risk

level but not eliminate the risk. Residual risk is discussed in Section 4.6.

Outputfrom Step 7—Residual risk

Figure 4-2 depicts the recommended methodology for risk mitigation.

^ NIST Interagency Report 4749, Sample Statements of Workfor Federal Computer Security Services: For Use In- House or Contracting Out. December 1991.

SP 800-30 Page 30
Input Risk Mitisation Activities Output

r

• Risk levels from the

risk assessment

report /

r N

• Risk assessment

report /

Step 1. Prioritize Actions

I

Step 2. Evaluate Recommended

Control Options

• Feasibility

• Effectiveness

Step 3. Conduct Cost-Benefit Analysis

• Impact of implanaiting

• Impact of not implementing

• Associated costs

Step 5. Assign Responsibility

I

Step 6. Develop Safeguard

Implementation Plan

• Risks and Associated Risk Levels

• Prioritized Actions

• Recommended Controls

• Selected Planned Controls

• Responsible Persons

• Start Date

• Target Completion Date

• Maintenance Requirements

I

Step 7. Implement Selected

Controls

Actions ranking from

High to Low

List of possible

controls

Cost-benefit analysis

Selected Controls

List of

responsible persons

Safeguard

implementation plan

Residual Risks

Figure 4-2. Risk Mitigation Methodology Flowchart

SP 800-30 Page 31
4.4 CONTROL CATEGORIES

In implementing recommended controls to mitigate risk, an organization should consider

technical, management, and operational security controls, or a combination of such controls, to

maximize the effectiveness of controls for their IT systems and organization. Security controls,

when used appropriately, can prevent, limit, or deter threat-source damage to an organization's

mission.

The control recommendation process will involve choosing among a combination of technical,

management, and operational controls for improving the organization's security posture. The

trade-offs that an organization will have to consider are illustrated by viewing the decisions

involved in enforcing use of complex user passwords to minimize password guessing and

cracking. In this case, a technical control requiring add-on security software may be more

complex and expensive than a procedural control, but the technical control is likely to be more

effective because the enforcement is automated by the system. On the other hand, a procedural

control might be implemented simply by means of a memorandum to all concerned individuals

and an amendment to the security guidelines for the organization, but ensuring that users

consistently follow the memorandum and guideline will be difficult and will require security

awareness training and user acceptance.

This section provides a high-level overview of some of the control categories. More detailed

guidance about implementing and planning for IT controls can be found in NIST SP 800-18,

Guide for Developing Security Plans for Information Technology Systems, and NIST SP 800-12,

An Introduction to Computer Security: The NIST Handbook.

Sections 4.4.1 through 4.4.3 provide an overview of technical, management, and operational

controls, respectively.

4.4.1 Technical Security Controls

Technical security controls for risk mitigation can be configured to protect against given types of

threats. These controls may range from simple to complex measures and usually involve system

architectures; engineering disciplines; and security packages with a mix of hardware, software,

and firmware. All of these measures should work together to secure critical and sensitive data,

information, and IT system functions. Technical controls can be grouped into the following

major categories, according to primary purpose:

• Support (Section 4.4.1.1). Supporting controls are generic and underlie most IT

security capabilities. These controls must be in place in order to implement other

controls.

• Prevent (Section 4.4.1.2). Preventive controls focus on preventing security breaches

from occurring in the first place.

• Detect and Recover (Section 4.4.1.3). These controls focus on detecting and

recovering from a security breach.

Figure 4-3 depicts the primary technical controls and the relationships between them.

SP 800-30 Page 32
Identillcation

Cryptographic Key Managonicnl

Seciiritv Administration i

System Protections

(least privilege, ohject reuse, process separalion, etc.)

Figure 4-3. Technical Security Controls

4.4.1.1 Supporting Technical Controls

Supporting controls are, by their very nature, pervasive and interrelated with many other

controls. The supporting controls are as follows:

• Identification. This control provides the ability to uniquely identify users, processes,

and information resources. To implement other security controls (e.g., discretionary access control [DAC], mandatory access control [MAC], accountability), it is

essential that both subjects and objects be identifiable.

• Cryptographic Key Management. Cryptographic keys must be securely managed

when cryptographic functions are implemented in various other controls.

Cryptographic key management includes key generation, distribution, storage, and

maintenance.

• Security Administration. The security features of an IT system must be configured

(e.g., enabled or disabled) to meet the needs of a specific installation and to account

for changes in the operational environment. System security can be built into

operating system security or the application. Commercial off-the-shelf add-on

security products are available.

SP 800-30 Page 33
• System Protections. Underlying a system's various security functional capabilities

is a base of confidence in the technical implementation. This represents the quality of

the implementation from the perspective both of the design processes used and of the

manner in which the implementation was accomplished. Some examples of system

protections are residual information protection (also known as object reuse), least

privilege (or "need to know"), process separation, modularity, layering, and

minimization of what needs to be trusted.

4.4.1.2 Preventive Technical Controls

These controls, which can inhibit attempts to violate security policy, include the following:

• Authentication. The authentication control provides the means of verifying the

identity of a subject to ensure that a claimed identity is valid. Authentication

mechanisms include passwords, personal identification numbers, or PESfs, and

emerging authentication technology that provides strong authentication (e.g., token,

smart card, digital certificate, Kerberos).

• Authorization. The authorization control enables specification and subsequent

management of the allowed actions for a given system (e.g., the information owner or

the database administrator determines who can update a shared file accessed by a group of online users).

• Access Control Enforcement. Data integrity and confidentiality are enforced by

access controls. When the subject requesting access has been authorized to access

particular processes, it is necessary to enforce the defined security policy (e.g., MAC

or DAC). These policy-based controls are enforced via access control mechanisms

distributed throughout the system (e.g., MAC sensitivity labels; DAC file permission

sets, access control lists, roles, user profiles). The effectiveness and the strength of

access control depend on the correctness of the access control decisions (e.g., how the

security rules are configured) and the strength of access control enforcement (e.g., the

design of software or hardware security).

• Nonrepudiation. System accountability depends on the ability to ensure that senders

cannot deny sending information and that receivers cannot deny receiving it. Nonrepudiation spans both prevention and detection. It has been placed in the

prevention category in this guide because the mechanisms implemented prevent the

successful repudiation of an action (e.g., the digital certificate that contains the

owner's private key is known only to the owner). As a result, this control is typically

applied at the point of transmission or reception.

• Protected Communications. In a distributed system, the ability to accomplish

security objectives is highly dependent on trustworthy communications. The

protected communications control ensures the integrity, availability, and

confidentiality of sensitive and critical information while it is in transit. Protected

communications use data encryption methods (e.g., virtual private network, Internet

Protocol Security [IPSEC] Protocol), and deployment of cryptographic technologies

(e.g.. Data Encryption Standard [DES], Triple DES, RAS, MD4, MD5, secure hash

standard, and escrowed encryption algorithms such as Clipper) to minimize network

threats such as replay, interception, packet sniffing, wiretapping, or eavesdropping. ]

I

i SP 800-30 Page 34

j i
• Transaction Privacy. Both government and private sector systems are increasingly

required to maintain the privacy of individuals. Transaction privacy controls (e.g.,

Secure Sockets Layer, secure shell) protect against loss of privacy with respect to

transactions performed by an individual.

4.4.1.3 Detection and Recovery Technical Controls

Detection controls warn of violations or attempted violations of security policy and include such

controls as audit trails, intrusion detection methods, and checksums. Recovery controls can be

used to restore lost computing resources. They are needed as a complement to the supporting

and preventive technical measures, because none of the measures in these other areas is perfect.

Detection and recovery controls include

• Audit. The auditing of security-relevant events and the monitoring and tracking of

system abnormalities are key elements in the after-the-fact detection of, and recovery

from, security breaches.

• Intrusion Detection and Containment. It is essential to detect security breaches

(e.g., network break-ins, suspicious activities) so that a response can occur in a timely

manner. It is also of little use to detect a security breach if no effective response can

be initiated. The intrusion detection and containment control provides these two

capabilities.

• Proof of Wholeness. The proof-of-wholeness control (e.g., system integrity tool)

analyzes system integrity and irregularities and identifies exposures and potential

threats. This control does not prevent violations of security policy but detects

violations and helps determine the type of corrective action needed.

• Restore Secure State. This service enables a system to return to a state that is

known to be secure, after a security breach occurs.

• Virus Detection and Eradication. Virus detection and eradication software installed

on servers and user workstations detects, identifies, and removes software viruses to

ensure system and data integrity.

4.4.2 Management Security Controls

Management security controls, in conjunction with technical and operational controls, are implemented to manage and reduce the risk of loss and to protect an organization's mission.

Management controls focus on the stipulation of information protection policy, guidelines, and

standards, which are carried out through operational procedures to fulfill the organization's goals

and missions.

Management security controls—preventive, detection, and recovery—that are implemented to

reduce risk are described in Sections 4.4.2.1 through 4.4.2.3.

SP 800-30 Page 35
4.4.2.1 Preventive Management Security Controls

These controls include the following:

• Assign security responsibility to ensure that adequate security is provided for the

mission-critical IT systems

• Develop and maintain system security plans to document current controls and address

planned controls for IT systems in support of the organization's mission

• Implement personnel security controls, including separation of duties, least privilege,

and user computer access registration and termination

• Conduct security awareness and technical training to ensure that end users and system

users are aware of the rules of behavior and their responsibilities in protecting the

organization's mission.

4.4.2.2 Detection Management Security Controls

Detection management controls are as follows:

• Implement personnel security controls, including personnel clearance, background

investigations, rotation of duties

• Conduct periodic review of security controls to ensure that the controls are effective

• Perform periodic system audits

• Conduct ongoing risk management to assess and mitigate risk

• Authorize IT systems to address and accept residual risk.

4.4.2.3 Recovery Management Security Controls

These controls include the following:

• Provide continuity of support and develop, test, and maintain the continuity of

operations plan to provide for business resumption and ensure continuity of

operations during emergencies or disasters

• Establish an incident response capability to prepare for, recognize, report, and

respond to the incident and return the IT system to operational status.

4.4.3 Operational Security Controls

An organization's security standards should establish a set of controls and guidelines to ensure

that security procedures governing the use of the organization's IT assets and resources are properly enforced and implemented in accordance with the organization's goals and mission.

Management plays a vital role in overseeing policy implementation and in ensuring the

establishment of appropriate operational controls.

SP 800-30 Page 36
Operational controls, implemented in accordance with a base set of requirements (e.g., technical

controls) and good industry practices, are used to correct operational deficiencies that could be

exercised by potential threat-sources. To ensure consistency and uniformity in security

operations, step-by-step procedures and methods for implementing operational controls must be

clearly defined, documented, and maintained. These operational controls include those presented

in Sections 4.4.3.1 and 4.4.3.2 below.

4.4.3.1 Preventive Operational Controls

Preventive operational controls are as follows:

• Control data media access and disposal (e.g., physical access control, degaussing

method)

• Limit external data distribution (e.g., use of labeling)

• Control software viruses

• Safeguard computing facility (e.g., security guards, site procedures for visitors,

electronic badge system, biometrics access control, management and distribution of

locks and keys, barriers and fences)

• Secure wiring closets that house hubs and cables

• Provide backup capability (e.g., procedures for regular data and system backups,

archive logs that save all database changes to be used in various recovery scenarios)

• Establish off-site storage procedures and security

• Protect laptops, personal computers (PC), workstations

• Protect IT assets from fire damage (e.g., requirements and procedures for the use of

fire extinguishers, tarpaulins, dry sprinkler systems, halon fire suppression system)

• Provide emergency power source (e.g., requirements for uninterruptible power

supplies, on-site power generators)

• Control the humidity and temperature of the computing facility (e.g., operation of air

conditioners, heat dispersal).

4.4.3.2 Detection Operational Controls

Detection operational controls include the following:

• Provide physical security (e.g., use of motion detectors, closed-circuit television

monitoring, sensors and alarms)

• Ensure environmental security (e.g., use of smoke and fire detectors, sensors and

alarms).

4.5 COST-BENEFIT ANALYSIS

To allocate resources and implement cost-effective controls, organizations, after identifying all

possible controls and evaluating their feasibility and effectiveness, should conduct a cost-benefit

SP 800-30 Page 37
analysis for each proposed control to determine which controls are required and appropriate for

their circumstances.

The cost-benefit analysis can be qualitative or quantitative. Its purpose is to demonstrate that the

costs of implementing the controls can be justified by the reduction in the level of risk. For

example, the organization may not want to spend $1,000 on a control to reduce a $200 risk.

A cost-benefit analysis for proposed new controls or enhanced controls encompasses the

following:

• Determining the impact of implementing the new or enhanced controls

• Determining the impact of not implementing the new or enhanced controls

• Estimating the costs of the implementation. These may include, but are not limited

to, the following: - Hardware and software purchases - Reduced operational effectiveness if system performance or functionality is

reduced for increased security - Cost of implementing additional policies and procedures - Cost of hiring additional personnel to implement proposed policies, procedures, or

services - Training costs - Maintenance costs

• Assessing the implementation costs and benefits against system and data criticality to

determine the importance to the organization of implementing the new controls, given

their costs and relative impact.

The organization will need to assess the benefits of the controls in terms of maintaining an

acceptable mission posture for the organization. Just as there is a cost for implementing a needed control, there is a cost for not implementing it. By relating the result of not

implementing the control to the mission, organizations can determine whether it is feasible to

forgo its implementation.

Cost-Benefit Analysis Example: System X stores and processes mission-critical and sensitive

employee privacy information; however, auditing has not been enabled for the system. A costbenefit analysis is conducted to determine whether the audit feature should be enabled for

System X.

Items (1) and (2) address the intangible impact (e.g., deterrence factors) for implementing or not

implementing the new control. Item (3) lists the tangibles (e.g., actual cost).

(1) Impact of enabling system audit feature: The system audit feature allows the system security

administrator to monitor users' system activities but will slow down system performance and i

therefore affect user productivity. Also the implementation will require additional resources, as described in Item 3.

j

I

SP 800-30 Page 38

I
(2) Impact of not enabling system audit feature: User system activities and violations cannot be

monitored and tracked if the system audit function is disabled, and security cannot be maximized

to protect the organization's confidential data and mission.

(3) Cost estimation for enabling the system audit feature:

Cost for enabling system audit feature—No cost, built-in feature $ 0

Additional staff to perform audit review and archive, per year $ xx,xxx

Training (e.g., system audit configuration, report generation) $ x,xxx

Add-on audit reporting software $ x,xxx

Audit data maintenance (e.g., storage, archiving), per year $ x,xxx

Total Estimated Costs $ xx,xxx

The organization's managers must determine what constitutes an acceptable level of mission

risk. The impact of a control may then be assessed, and the control either included or excluded,

after the organization determines a range of feasible risk levels. This range will vary among

organizations; however, the following rules apply in determining the use of new controls:

• If control would reduce risk more than needed, then see whether a less expensive

alternative exists

• If control would cost more than the risk reduction provided, then find something else

• If control does not reduce risk sufficiently, then look for more controls or a different

control

• If control provides enough risk reduction and is cost-effective, then use it.

Frequently the cost of implementing a control is more tangible than the cost of not implementing

it. As a result, senior management plays a critical role in decisions concerning the

implementation of control measures to protect the organizational mission.

4.6 RESIDUAL RISK

Organizations can analyze the extent of the risk reduction generated by the new or enhanced

controls in terms of the reduced threat likelihood or impact, the two parameters that define the

mitigated level of risk to the organizational mission.

Implementation of new or enhanced controls can mitigate risk by

• Eliminating some of the system's vulnerabilities (flaws and weakness), thereby

reducing the number of possible threat-source/vulnerability pairs

• Adding a targeted control to reduce the capacity and motivation of a threat-source

For example, a department determines that the cost for installing and maintaining

add-on security software for the stand-alone PC that stores its sensitive files is not

justifiable, but that administrative and physical controls should be implemented to

SP 800-30 Page 39
make physical access to that PC more difficult (e.g., store the PC in a locked room,

with the key kept by the manager).

• Reducing the magnitude of the adverse impact (for example, limiting the extent of a

vulnerability or modifying the nature of the relationship between the IT system and

the organization's mission).

The relationship between control implementation and residual risk is graphically presented in

Figure 4-4.

Figure 4-4. Implemented Controls and Residual Risk

The risk remaining after the implementation of new or enhanced controls is the residual risk.

Practically no IT system is risk free, and not all implemented controls can eliminate the risk they

are intended to address or reduce the risk level to zero.

As mandated by 0MB Circular A-130, an organization's senior management or the DAA, who

are responsible for protecting the organization's IT asset and mission, must authorize (or

accredit) the IT system to begin or continue to operate. This authorization or accreditation must

occur at least every 3 years or whenever major changes are made to the IT system. The intent of

this process is to identify risks that are not fully addressed and to determine whether additional

controls are needed to mitigate the risks identified in the IT system. For federal agencies, after

the appropriate controls have been put in place for the identified risks, the DAA will sign a statement accepting any residual risk and authorizing the operation of the new IT system or the

continued processing of the existing IT system. If the residual risk has not been reduced to an

acceptable level, the risk management cycle must be repeated to identify a way of lowering the

residual risk to an acceptable level.

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5. EVALUATION AND ASSESSMENT

In most organizations, the network itself will continually be expanded and updated, its

components changed, and its software applications replaced or updated with newer versions. In

addition, personnel changes will occur and security policies are likely to change over time.

These changes mean that new risks will surface and risks previously mitigated may again

become a concern. Thus, the risk management process is ongoing and evolving.

This section emphasizes the good practice and need for an ongoing risk evaluation and

assessment and the factors that will lead to a successful risk management program.

5.1 GOOD SECURITY PRACTICE

The risk assessment process is usually repeated at least every 3 years for federal agencies, as mandated by OMB Circular A- 130. However, risk management should be conducted and

integrated in the SDLC for IT systems, not because it is required by law or regulation, but

because it is a good practice and supports the organization's business objectives or mission.

There should be a specific schedule for assessing and mitigating mission risks, but the

periodically performed process should also be flexible enough to allow changes where

warranted, such as major changes to the IT system and processing environment due to changes

resulting from policies and new technologies.

5.2 KEYS FOR SUCCESS

A successful risk management program will rely on (1) senior management's commitment; (2)

the full support and participation of the IT team (see Section 2.3); (3) the competence of the risk

assessment team, which must have the expertise to apply the risk assessment methodology to a

specific site and system, identify mission risks, and provide cost-effective safeguards that meet

the needs of the organization; (4) the awareness and cooperation of members of the user community, who must follow procedures and comply with the implemented controls to

safeguard the mission of their organization; and (5) an ongoing evaluation and assessment of the

IT-related mission risks.

SP 800-30 Page 41
f
APPENDIX A: Sample Interview Questions

Interview questions should be tailored based upon where the IT system assessed is in the SDLC.

Sample questions to be asked during interviews with site personnel to gain an understanding of

the operational characteristics of an organization may include the following:

• Who are valid users?

• What is the mission of the user organization?

• What is the purpose of the system in relation to the mission?

• How important is the system to the user organization's mission?

• What is the system-availability requirement?

• What information (both incoming and outgoing) is required by the organization?

• What information is generated by, consumed by, processed on, stored in, and

retrieved by the system?

• How important is the information to the user organization's mission?

• What are the paths of information flow?

• What types of information are processed by and stored on the system (e.g., financial,

personnel, research and development, medical, command and control)?

• What is the sensitivity (or classification) level of the information?

• What information handled by or about the system should not be disclosed and to

whom?

• Where specifically is the information processed and stored?

• What are the types of information storage?

• What is the potential impact on the organization if the information is disclosed to

unauthorized personnel?

• What are the requirements for information availability and integrity?

• What is the effect on the organization's mission if the system or information is not

reliable?

• How much system downtime can the organization tolerate? How does this downtime

compare with the mean repair/recovery time? What other processing or communications options can the user access?

• Could a system or security malfunction or unavailability result in injury or death?

SP 800-30 Page A-1
I
APPENDIX B: SAMPLE RISK ASSESSMENT REPORT OUTLINE

EXECUTIVE SUMMARY

I. Introduction

• Purpose

• Scope of this risk assessment

Describe the system components, elements, users, field site locations (if any), and any other

details about the system to be considered in the assessment.

II. Risk Assessment Approach

Briefly describe the approach used to conduct the risk assessment, such as

• The participants (e.g., risk assessment team members)

• The technique used to gather information (e.g., the use of tools, questionnaires)

• The development and description of risk scale (e.g., a3x3, 4x4, or 5x5 risk-level

matrix).

in. System Characterization

Characterize the system, including hardware (server, router, switch), software (e.g., application,

operating system, protocol), system interfaces (e.g., communication link), data, and users. Provide connectivity diagram or system input and output flowchart to delineate the scope of this

risk assessment effort.

IV. Threat Statement

Compile and list the potential threat-sources and associated threat actions applicable to the

system assessed.

V. Risk Assessment Results

List the observations (vulnerability/threat pairs). Each observation must include

• Observation number and brief description of observation (e.g.. Observation 1: User

system passwords can be guessed or cracked)

• A discussion of the threat-source and vulnerability pair

• Identification of existing mitigating security controls

• Likelihood discussion and evaluation (e.g.. High, Medium, or Low likelihood)

• Impact analysis discussion and evaluation (e.g.. High, Medium, or Low impact)

• Risk rating based on the risk-level matrix (e.g., High, Medium, or Low risk level)

• Recommended controls or alternative options for reducing the risk.

VI. Summary

Total the number of observations. Summarize the observations, the associated risk levels, the

SP 800-30 PageB-1
recommendations, and any comments in a table format to facilitate the implementation of

recommended controls during the risk mitigation process.

SP 800-30

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SP 800-30 Page C-1
II
APPENDIX D: ACRONYMS

AES Advanced Encryption Standard

CSA Computer Security Act

DAA Designated Approving Authority

DAC Discretionary Access Control

DBS Data Encryption Standard

FedCIRC Federal Computer Incident Response Center

FTP File Transfer Protocol

ID Identifier

IPSEC Internet Security Protocol

ISSO Information system security officer

IT Information Technology

ITL Information Technology Laboratory

MAC Mandatory Access Control

NIPC National Infrastructure Protection Center

NIST National Institute of Standards and Technology

OIG Office of Inspector General

0MB Office of Management and Budget

PC Personal Computer

SDLC System Development Life Cycle

SP Special Publication

ST&E Security Test and Evaluation

SP 800-30
I
APPENDIX E: GLOSSARY

TERM

Accountability

Assurance

Availability

Confidentiality

Denial of Service

Due Care

Integrity

DEFINITION

The security goal that generates the requirement for actions of an entity to

be traced uniquely to that entity. This supports nonrepudiation, deterrence,

fault isolation, intrusion detection and prevention, and after-action recovery

and legal action.

Grounds for confidence that the other four security goals (integrity,

availability, confidentiality, and accountability) have been adequately met

by a specific implementation. "Adequately met" includes (1) functionality

that performs correctly, (2) sufficient protection against unintentional errors (by users or software), and (3) sufficient resistance to intentional penetration or bypass.

The security goal that generates the requirement for protection against

• Intentional or accidental attempts to (1) perform unauthorized deletion

of data or (2) otherwise cause a denial of service or data

• Unauthorized use of system resources.

The security goal that generates the requirement for protection from

intentional or accidental attempts to perform unauthorized data reads.

Confidentiality covers data in storage, during processing, and in transit.

The prevention of authorized access to resources or the delaying of timecritical operations.

Managers and their organizations have a duty to provide for information

security to ensure that the type of control, the cost of control, and the

deployment of control are appropriate for the system being managed.

The security goal that generates the requirement for protection against either

intentional or accidental attempts to violate data integrity (the property that

data has when it has not been altered in an unauthorized manner) or system

integrity (the quality that a system has when it performs its intended

function in an unimpaired manner, free from unauthorized manipulation).

SP 800-30 Page E-1
IT-Related Risk

IT Security Goal

Risk

Risk Assessment

Risk Management

Security

Security Goals

Threat

Threat-source

Threat Analysis

Vulnerability

SP 800-30

The net mission impact considering (1) the probability that a particular

threat-source will exercise (accidentally trigger or intentionally exploit) a

particular information system vulnerability and (2) the resulting impact if

this should occur. IT-related risks arise from legal liability or mission loss

due to

1 . Unauthorized (malicious or accidental) disclosure, modification, or

destruction of information

2. Unintentional errors and omissions

3. IT disruptions due to natural or man-made disasters

4. Failure to exercise due care and diligence in the implementation and

operation of the IT system.

See Security Goals

Within this document, synonymous with IT-Related Risk.

The process of identifying the risks to system security and determining the

probability of occurrence, the resulting impact, and additional safeguards

that would mitigate this impact. Part of Risk Management and synonymous

with Risk Analysis.

The total process of identifying, controlling, and mitigating information

system-related risks. It includes risk assessment; cost-benefit analysis; and

the selection, implementation, test, and security evaluation of safeguards.

This overall system security review considers both effectiveness and

efficiency, including impact on the mission and constraints due to policy,

regulations, and laws.

Information system security is a system characteristic and a set of

mechanisms that span the system both logically and physically.

The five security goals are integrity, availability, confidentiality,

accountability, and assurance.

The potential for a threat-source to exercise (accidentally trigger or

intentionally exploit) a specific vulnerability.

Either (1) intent and method targeted at the intentional exploitation of a

vulnerability or (2) a situation and method that may accidentally trigger a

vulnerability.

The examination of threat-sources against system vulnerabilities to

determine the threats for a particular system in a particular operational

environment.

A flaw or weakness in system security procedures, design, implementation,

or internal controls that could be exercised (accidentally triggered or

intentionally exploited) and result in a security breach or a violation of the

system's security policy.

Page E-2
APPENDIX F: REFERENCES

Computer Systems Laboratory Bulletin. Threats to Computer Systems: An Overview.

March 1994.

NIST Interagency Reports 4749. Sample Statements of Workfor Federal Computer Security

Services: For Use In-House or Contracting Out. December 1991.

NIST Special Publication 800-12. An Introduction to Computer Security: The NIST Handbook.

October 1995.

NIST Special Publication 800-14. Generally Accepted Principles and Practices for Securing

Information Technology Systems. September 1996. Co-authored with Barbara Guttman.

NIST Special Publication 800-18. Guide For Developing Security Plans for Information

Technology Systems. December 1998. Co-authored with Federal Computer Security Managers'

Forum Working Group.

NIST Special Publication 800-26, Security Self-Assessment Guide for Information Technology

Systems. August 2001.

NIST Special Publication 800-27. Engineering Principles for IT Security. June 2001.

0MB Circular A- 130. Management of Federal Information Resources. Appendix HI.

November 2000.

SP 800-30 Page F-1
1
Technical Publications

Periodical

Journal of Research of the National Institute of Standards and Technology—Reports NIST research

and development in those disciplines of the physical and engineering sciences in which the Institute is

active. These include physics, chemistry, engineering, mathematics, and computer sciences. Papers cover a broad range of subjects, with major emphasis on measurement methodology and the basic technology

underlying standardization. Also included from time to time are survey articles on topics closely related to the Institute's technical and scientific programs. Issued six times a year.

Nonperiodicals

Monographs—Major contributions to the technical literature on various subjects related to the Institute's

scientific and technical activities. Handbooks—Recommended codes of engineering and industrial practice (including safety codes)

developed in cooperation with interested industries, professional organizations, and regulatory bodies.

Special Publications—Include proceedings of conferences sponsored by NIST, NIST annual reports, and

other special publications appropriate to this grouping such as wall charts, pocket cards, and bibliographies.

National Standard Reference Data Series—Provides quantitative data on the physical and chemical

properties of materials, compiled from the world's literature and critically evaluated. Developed under a worldwide program coordinated by NIST under the authority of the National Standard Data Act (Public

Law 90-396). NOTE: The Journal of Physical and Chemical Reference Data (JPCRD) is published

bimonthly for NIST by the American Institute of Physics (AIP). Subscription orders and renewals are available from AIP, P.O. Box 503284, St. Louis, MO 63150-3284.

Building Science Series—Disseminates technical information developed at the Institute on building

materials, components, systems, and whole structures. The series presents research results, test methods,

and performance criteria related to the structural and environmental functions and the durability and safety

characteristics of building elements and systems.

Technical Notes—Studies or reports which are complete in themselves but restrictive in their treatment of

a subject. Analogous to monographs but not so comprehensive in scope or definitive in treatment of the

subject area. Often serve as a vehicle for final reports of work performed at NIST under the sponsorship of

other government agencies.

Voluntary Product Standards—Developed under procedures published by the Department of Commerce

in Part 10, Title 15, of the Code of Federal Regulations. The standards establish nationally recognized

requirements for products, and provide all concerned interests with a basis for common understanding of

the characteristics of the products. NIST administers this program in support of the efforts of private-sector

standardizing organizations.

Order the following NISTpublications—FIPS and NISTIRs—from the National Technical Information

Service, Springfield, VA 22161.

Federal Information Processing Standards Publications (FIPS PUB)—Publications in this series

collectively constitute the Federal Information Processing Standards Register. The Register serves as the

official source of information in the Federal Government regarding standards issued by NIST pursuant to the Federal Property and Administrative Services Act of 1949 as amended. Public Law 89-306 (79 Stat. 1127), and as implemented by Executive Order 11717 (38 FR 12315, dated May 11, 1973) andPart6of

Title 15 CFR (Code of Federal Regulations).

NIST Interagency or Internal Reports (NISTIR)—The series includes interim or final reports on work

performed by NIST for outside sponsors (both goverrunent and nongovernment). In general, initial distribution is handled by the sponsor; public distribution is handled by sales through the National

Technical Information Service, Springfield, VA 22161, in hard copy, electronic media, or microfiche form.

NISTIR' s may also report results of NIST projects of transitory or limited interest, including those that will

be published subsequently in more comprehensive form.
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