Patent Publication Number: US-2023153433-A1

Title: System and Method for Recent File Malware Scanning

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of co-pending U.S. patent application Ser. No. 17/529,395, filed Nov. 18, 2021, the entire contents of which are incorporated herein by reference. 
    
    
     FIELD 
     The invention relates generally to computer security, and more particularly to identifying security issues in Internet downloaded files. 
     BACKGROUND 
     The traditional line of defense against malware is composed of malware detectors such as virus and spyware scanners. The scanners decide if a scanned data file is a threat, based on the data they collect on it. The data may be collected with or without executing the scanned data file. Static analysis is a process of collecting and analyzing data file descriptions (e.g. file format descriptions, code description, binary data, text strings, information extracted via code emulation and other similar data) without actually running (executing) the code. Static analysis is generally performed by determining the signature of the binary file which is a unique identification for the binary file and can be done by calculating the cryptographic hash of the file and understanding each component. It is generally considered that static analysis is safe for the user—the malware can be detected before it starts to act on a real user&#39;s machine. 
     SUMMARY 
     Systems and methods for recently downloaded Internet files malware scanning are provided herein. In some embodiments, a system includes an input/output device, a storage device, and a processor programmed to download one or more files via the input/output device to the storage device, filter, by a first driver, the one or more downloaded files using a security zone identifier associated with each of the one or more downloaded files to produce a filtered subset of one or more files, scan, by the first driver , the filtered subset of one or more files for malware, store, by a second driver in an alternative data stream (ADS), a first set of information associated with each of the scanned files to indicate that each the filtered subset of one or more files have been scanned, monitor, by a second driver, changes to existing files on the storage device based on a comparison of the information associated with the existing files stored and the information stored associated with the existing files in the alternative data stream file, and send instructions to rescan any existing file that has changed for malware, and update the information associated with any rescanned filed in the alternative data stream file. 
     In other embodiments, the system includes an input/output device, a storage device, and a processor programmed to receive files via the input/output device to the storage device, detect if any processes are trying to write to other files on the system, and if so, check if the detected file has been scanned before using an alternative-stream database, if the detected file matches the alternative-stream database, the detected file is allowed and noted as clean, if the detected file fails to match the alternative-stream database, the detected file is scanned and marked as scanned until the detected file changes again, re-scan the detected file that changed again using the alternative-stream database, and if the detected file matches the alternative-stream database, the detected file is allowed and noted as clean, and if the detected file fails to match the alternative-stream database, the detected file that changed again is disabled, and transmit the results of the rescan to the input/output device. 
     Other and further embodiments in accordance with the present principles are described below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present principles can be understood in detail, a more particular description of the principles, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments in accordance with the present principles and are therefore not to be considered limiting of its scope, for the principles may admit to other equally effective embodiments. 
         FIG.  1    depicts a high-level block diagram of a network architecture of a system for efficient security scanning of recently downloaded files from the Internet into a computer system in accordance with an embodiment of the present principles. 
         FIG.  2    depicts a flow diagram of a method for efficient security scanning of recently downloaded files from the Internet into a computer system, in accordance with an embodiment of the present principles. 
         FIG.  3    depicts a flow diagram of a method for efficient security scanning of recently downloaded files from the Internet into a computer system, in accordance with an embodiment of the present principles. 
         FIG.  4    depicts another flow diagram of a method for efficient security scanning of recently downloaded files from the Internet into a computer system, in accordance with an embodiment of the present principles. 
         FIG.  5    depicts a high-level block diagram of a computing device suitable for use with embodiments for efficient security scanning of recently downloaded files from the Internet into a computer system in accordance with the present principles. 
         FIGS.  6 - 8    depict additional flow diagrams of a method for efficient security scanning of recently downloaded files from the Internet into a computer system, in accordance with an embodiment of the present principles. 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. 
     DETAILED DESCRIPTION 
     The following detailed description describes techniques (e.g., methods, processes, and systems) for efficiently security scanning recently downloaded files from the Internet into a computer system. While the concepts of the present principles are susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and are described in detail below. It should be understood that there is no intent to limit the concepts of the present principles to the particular forms disclosed. On the contrary, the intent is to cover all modifications, equivalents, and alternatives consistent with the present principles and the appended claims. 
     Embodiments consistent with the invention use a solution that works with recently downloaded files from the Internet as the recently downloaded files are the most likely sources of malware. Such a system is more efficient when compared to traditional static analysis systems that scan all downloaded files thereby using a large number of computational resources, and the more files that are scanned, the more resources are used up. 
     In some embodiments, system  100  is implemented via drivers that filter and scan only recently downloaded files  108  based on associated metadata (e.g., security zone identifier (.Zone.Identifier)). System  100  then checks the downloaded files  108  for malware and marks them with a signature  110  that they&#39;ve been scanned, and the same files will need to be rechecked. System  100  hashes the checked file  108  and keeps the hash for future reference. Upon rescan of the files  108 , system  100  is able to compare the hash values and detect whether the file has been changed, and if so, the system rechecks the file. 
     For example with reference to  FIG.  1   , in some embodiments, system  100  includes an input/output device  102 , a storage device  104 , and a processor  106  programmed to download one or more files  108  via the input/output device to the storage device. In some embodiments, the system  100  first filters, by a first driver  112 , the one or more downloaded files  108  using associated metadata and/or Internet capabilities of the invoking process (e.g. security zone identifier associated with each of the one or more downloaded files) to produce a filtered subset of one or more files. The first driver then scans the filtered subset of one or more files for malware. The first driver  112  may be a native operating system driver or other type of generic malware scanner. 
     The system  100  then stores, by a second driver  114 , a first set of information associated with each of the scanned files  108  to indicate that each of the filtered subset of one or more files have been scanned. In some embodiments, the first set of information is stored as metadata associated with a file. The metadata may be stored using an Alternate Data Stream or as part of general purpose data storage. Alternate data streams (ADS), also known as NTFS file streams, are part of every file, as well as directories (folders), in a Windows NTFS volume, or example. Files and folders are comprised of attributes one of which is $Data. The content normally associated with a file such as the text in a .txt file or the executable code in a .exe file is stored in the ‘default’ $Data attribute or ‘stream’. The name string of this default attribute is empty (set to “ ”) thus it is often referred to as the “unnamed data stream”. Any additional $Data steams must be named and are typically referred to as “alternate data streams”. The ADS may contain metadata information, such as, for example, one or more of the following: data locating a specific file by author or title, a security zone identifier, an indication as to whether a filed has been scanned, the date of the last scan, the results of the last scan, a scan time, a file size, a cryptographic hash signature, and the like. 
     The system  100  then monitors, by the second driver, changes to existing files on the storage device  104  based on a comparison of the information associated with the existing file&#39;s metadata and the information stored within the associated file&#39;s metadata (e.g. stored in the ADS). Based on the changes found, the system  100  sends instructions to rescan any existing file which a change has been detected for malware, and updates the information associated with any rescanned file in the file&#39;s metadata (e.g. written using ADS). 
     In some embodiments, the security zone identifier identifies a file origin of where the one or more downloaded files  108  are downloaded from. In some embodiments, the security zone identifier is a Zone.Identifier including a numerical value that identifies a file origin as one of: 0 for Local Machine Zone, 1 for Local Intranet Zone, 2 for Trusted Sites Zone, 3 for Internet Zone, and 4 for Restricted Sites Zone. 
     In some embodiments, files  108  identified as having a security zone identifier that indicates the file is from an Internet zone are included in the filtered subset of files. In some embodiments, the first driver  112  is a native file system driver. In some embodiments, the second driver  114  is a custom file system monitoring application driver, also referred to as an M-Shield driver herein). In some embodiments, the first driver  112  further filters the one or more downloaded files  108  using a download timestamp to produce the filtered subset of files. 
     In some embodiments, only files  108  having a download timestamp less than a predefined threshold are scanned. In some embodiments, the predefined threshold is defined by all the files that are downloaded and not scanned from the time of the application started. 
     In some embodiments, the first set of information stored as metadata in an ADS associated with each of the scanned file includes one or more of a file name, an indication of whether the file was previously scanned, results of the last scan, a scan time, a file size, or a cryptographic hash signature  110  of the file  108 . 
     In some embodiments, the system  100  prioritizes files  108  that are executable over any other file type for scanning and rescanning. In some embodiments, the alternative data stream file associated with each file  108  is produced on startup of the system  100 . In some embodiments, the system  100  includes a scoring system to determine how often and if any of the files  108  need to be rechecked. 
     In some embodiments, the scoring system is based upon at least one of each file&#39;s  108  source, creation date, and directory. In some embodiments, the scoring system determines at least one type of scanning, type of checking method, and scanning priority. In some embodiments, each file  108  that was changed is rehashed and the rehash is stored for a later comparison. 
     In some embodiments, the system  100  includes an input/output device  102  and a storage device  104 . The system  100  also includes a processor  106  programmed to receive files  108  at the storage device  104  via the input/output device  102 . With additional reference to  FIG.  8   , the processor  106  detects if any processes are trying to write to other files  115  on the system  100 , and if so, checks if the detected file has been scanned before using file&#39;s metadata (e.g. written using ADS), if the detected file matches the alternative-stream database  116 , the detected file is allowed and noted as clean, if the detected file fails to match the alternative-stream database  116 , the detected file is scanned and marked as scanned until the detected file changes again. The processor  106  re-scans the detected file that changed again using the alternative-stream database  116 , and if the detected file matches the alternative-stream database  116 , the detected file is allowed and noted as clean, and if the detected file fails to match the alternative-stream database  116 , the detected file that changed again is disabled. The processor  106  transmits the results of the rescan to the input/output device  102 . 
     In some embodiments, the system  100  prioritizes files that are executable over any other file type. In some embodiments, the alternative-stream database  116  is produced on startup of the system  100 . For instance, on startup the system  100  determines the state of each file on the system. So in this case, system  100  uses the hash to reconstruct our understanding of the system, of the files on the system. 
     More in particular and with reference to  FIG.  6   , in some embodiments, the second driver  114 , e.g. MSHIELD, registers itself as a mini-filter in with the Microsoft filter manager of system  100 . This registration on the Windows platform is an initial stage of driver  114  to enable the start accepting notifications about file(s)  108  activities on system  100 . In other words, drive  114  is a Window&#39;s mini-filter driver that monitors file(s)  108  activities. 
     In some embodiments, the alternative-stream database  116  is generated by a determination of which files  108  were recently received based upon alternative-stream data carried by each respective file, using an alternative-stream data threshold that filters which files are considered, scanning the files that were filtered for malware, marking each of those files as scanned, generating a hash for each file that was scanned, storing each hash in the alternative-stream database, re-scanning each of the files that was scanned and comparing each file re-scanned with its respective stored hash to detect if any individual file was changed based upon this comparison, and any file that was detected to have changed is re-checked to assess the security risk the file presents to the system  100 . 
     In some embodiments, the alternative-stream data uses Zone.Identifier for Microsoft based operation systems as well as using at least one of fanotify and inotify Application Programming Interfaces that enables system  100  to monitor filesystem events in Linux and Android. For instance and with reference to  FIG.  7   , the source of the file  108  is checked after a write request is made by system  100  and the second driver  114  determines if the write request has advertisements as an initial parameter. In some embodiments, the alternative-stream data uses Zone.Identifier for Microsoft based operation systems as well as using at least one of fanotify and inotify Application Programming Interfaces that enables system  100  to monitor filesystem events in Linux and Android. For instance and with reference to  FIG.  7   , the source of the file  108  is checked after a write request is made by system  100  and the second driver  114  determines if the write request has advertisements as an initial parameter. A fanotify notification group is a kernel-internal object that holds a list of files, directories, filesystems, and mounts for which events shall be created. Meanwhile, the inotify API provides a mechanism for monitoring filesystem events. Inotify can be used to monitor individual files, or to monitor directories. 
     In some embodiments, the system  100  includes a scoring system to determine how often and if any of the files  108  need to be rechecked. In some embodiments, the scoring system is based upon at least one of each file&#39;s  108  source, creation date, and directory. In some embodiments, the scoring system determines at least one type of scanning, type of checking method, and scanning priority. In some embodiments, each file  108  that was changed is rehashed and the rehash is stored for a later comparison. 
     In some embodiment, the system  100  communicates over a communications network  122 , which enables a signal to travel anywhere within system  100  and/or to any other component/system connected to the system. The communications network  122  is wired and/or wireless, for example. The communications network  122  is local and/or global with respect to system  100 , for instance. 
       FIGS.  2 - 4    illustrate example flow diagrams representing one or more of the processes as described herein. Each block of the flow diagram may represent a module of code to execute and/or combinations of hardware and/or software configured to perform one or more processes described herein. Though illustrated in a particular order, the following figures are not meant to be so limiting. Any number of blocks may proceed in any order (including being omitted) and/or substantially simultaneously (i.e., within technical tolerances of processors, etc.) to perform the operations described herein. 
       FIG.  2    is an example process  200  a flow diagram of a method for efficient security scanning of recently downloaded files from the Internet into a computer system, in accordance with an embodiment of the present principles. Such a process  200  may begin at  202  by downloading one or more files via the input/output device to the storage device. The method may also include filtering, by a first driver, the one or more downloaded files using a security zone identifier associated with each of the one or more downloaded files to produce a filtered subset of one or more files at  204 . The method may additionally include scanning, by the first driver, the filtered subset of one or more files for malware at  206 . The method also includes storing, by a second driver in the associated file&#39;s metadata (e.g. using ADS), a first set of information associated with each of the scanned files to indicate that each of the filtered subset of one or more files have been scanned at  208 . The method further includes monitoring, by the second driver, changes to existing files on the storage device based on a comparison of the information associated with the existing files stored and the information stored associated with the existing files in the associated file&#39;s metadata (e.g. using ADS), and sends instructions to rescan any existing file that has changed for malware at  210 . The method additionally includes updating the information associated with any rescanned file in the alternative data stream file at  212 . 
       FIG.  3    depicts a flow diagram of another method  300  for efficient security scanning of recently downloaded files from the Internet into a computer system. The method begins at  302  by receiving files at the storage device via the input/output device. The method also includes detecting if any processes are trying to write to other files on the system, and if so, check if the detected file has been scanned before using an alternative-stream database, if the detected file matches the alternative-stream database, the detected file is allowed and noted as clean, if the detected file fails to match the alternative-stream database, the detected file is scanned and marked as scanned until the detected file changes again at  304 . The method further includes re-scanning the detected file that changed again using the alternative-stream database, and if the detected file matches the alternative-stream database, the detected file is allowed and noted as clean, and if the detected file fails to match the alternative-stream database, the detected file that changed again is disabled at  306 . The method additionally includes transmitting the results of the rescan to the input/output device at  308 . 
       FIG.  4    depicts a flow diagram of another method  400  for efficient security scanning of recently downloaded files from the Internet into a computer system. The method begins at  402  by receiving files at the storage device via the input/output device. The method also includes detecting if any processes are trying to write to other files on the system, and if so, check if the detected file has been scanned before using an alternative-stream database, if the detected file matches the alternative-stream database, the detected file is allowed and noted as clean, if the detected file fails to match the alternative-stream database, the detected file is scanned and marked as scanned until the detected file changes again at  404 . The method further includes re-scanning the detected file that changed again using the alternative-stream database, and if the detected file matches the alternative-stream database, the detected file is allowed and noted as clean, and if the detected file fails to match the alternative-stream database, the detected file that changed again is disabled at  406 . The method additionally includes generating the alternative data base by a determination of which files were recently received based upon alternative-stream data carried by each respective file, using an alternative-stream data threshold that filters which files are considered, scanning the files that were filtered for malware, marking each of those files as scanned, generating a hash for each file that was scanned, storing each hash in the alternative-stream database, re-scanning each of the files that was scanned and comparing each file re-scanned with its respective stored hash to detect if any individual file was changed based upon this comparison, and any file that was detected to have changed is re-checked to assess the security risk the file presents to the system at  408 . The method also includes transmitting the results of the rescan to the input/output device at  410 . 
       FIG.  5    depicts a computer system  500  that can be utilized in various embodiments of the invention to implement the computer and/or the display, according to one or more embodiments. 
     Various embodiments of method and system to identify security issues in downloaded files such as from the Internet, as described herein, may be executed on one or more computer systems, which may interact with various other devices. One such computer system is computer system  500  illustrated by  FIG.  5   , which may in various embodiments implement any of the elements or functionality illustrated in  FIGS.  1 - 4   . In various embodiments, computer system  500  may be configured to implement methods described above. The computer system  500  may be used to implement any other system, device, element, functionality or method of the above-described embodiments. In the illustrated embodiments, computer system  500  may be configured to implement the methods  200 ,  300  and  400  as processor-executable executable program instructions  522  (e.g., program instructions executable by processor(s)  510 ) in various embodiments. 
     In the illustrated embodiment, computer system  500  includes one or more processors  510   a - 510   n  coupled to a system memory  520  via an input/output (I/O) interface  530 . Computer system  500  further includes a network interface  540  coupled to I/O interface  530 , and one or more input/output devices  550 , such as cursor control device  560 , keyboard  570 , and display(s)  580 . In various embodiments, any of the components may be utilized by the system to receive user input described above. In various embodiments, a user interface may be generated and displayed on display  580 . In some cases, it is contemplated that embodiments may be implemented using a single instance of computer system  500 , while in other embodiments multiple such systems, or multiple nodes making up computer system  500 , may be configured to host different portions or instances of various embodiments. For example, in one embodiment some elements may be implemented via one or more nodes of computer system  500  that are distinct from those nodes implementing other elements. In another example, multiple nodes may implement computer system  500  in a distributed manner. 
     In different embodiments, computer system  500  may be any of various types of devices, including, but not limited to, a personal computer system, desktop computer, laptop, notebook, tablet or netbook computer, mainframe computer system, handheld computer, workstation, network computer, a camera, a set top box, a mobile device, a consumer device, video game console, handheld video game device, application server, storage device, a peripheral device such as a switch, modem, router, or in general any type of computing or electronic device. 
     In various embodiments, computer system  500  may be a uniprocessor system including one processor  510 , or a multiprocessor system including several processors  510  (e.g., two, four, eight, or another suitable number). Processors  510  may be any suitable processor capable of executing instructions. For example, in various embodiments processors  510  may be general-purpose or embedded processors implementing any of a variety of instruction set architectures (ISAs). In multiprocessor systems, each of processors  510  may commonly, but not necessarily, implement the same ISA. 
     System memory  520  may be configured to store program instructions  522  and/or data  532  accessible by processor  510 . In various embodiments, system memory  520  may be implemented using any suitable memory technology, such as static random-access memory (SRAM), synchronous dynamic RAM (SDRAM), nonvolatile/Flash-type memory, or any other type of memory. In the illustrated embodiment, program instructions and data implementing any of the elements of the embodiments described above may be stored within system memory  520 . In other embodiments, program instructions and/or data may be received, sent or stored upon different types of computer-accessible media or on similar media separate from system memory  520  or computer system  500 . 
     In one embodiment, I/O interface  530  may be configured to coordinate I/O traffic between processor  510 , system memory  520 , and any peripheral devices in the device, including network interface  540  or other peripheral interfaces, such as input/output devices  550 . In some embodiments, I/O interface  530  may perform any necessary protocol, timing or other data transformations to convert data signals from one component (e.g., system memory  520 ) into a format suitable for use by another component (e.g., processor  510 ). In some embodiments, I/O interface  530  may include support for devices attached through various types of peripheral buses, such as a variant of the Peripheral Component Interconnect (PCI) bus standard or the Universal Serial Bus (USB) standard, for example. In some embodiments, the function of I/O interface  530  may be split into two or more separate components, such as a north bridge and a south bridge, for example. Also, in some embodiments some or all of the functionality of I/O interface  530 , such as an interface to system memory  520 , may be incorporated directly into processor  510 . 
     Network interface  540  may be configured to allow data to be exchanged between computer system  500  and other devices attached to a network (e.g., network  590 ), such as one or more external systems or between nodes of computer system  500 . In various embodiments, network  590  may include one or more networks including but not limited to Local Area Networks (LANs) (e.g., an Ethernet or corporate network), Wide Area Networks (WANs) (e.g., the Internet), wireless data networks, some other electronic data network, or some combination thereof In various embodiments, network interface  540  may support communication via wired or wireless general data networks, such as any suitable type of Ethernet network, for example; via digital fiber communications networks; via storage area networks such as Fiber Channel SANs, or via any other suitable type of network and/or protocol. 
     Input/output devices  550  may, in some embodiments, include one or more display terminals, keyboards, keypads, touchpads, scanning devices, voice or optical recognition devices, or any other devices suitable for entering or accessing data by one or more computer systems  500 . Multiple input/output devices  550  may be present in computer system  500  or may be distributed on various nodes of computer system  500 . In some embodiments, similar input/output devices may be separate from computer system  500  and may interact with one or more nodes of computer system  500  through a wired or wireless connection, such as over network interface  540 . 
     In some embodiments, the illustrated computer system may implement any of the operations and methods described above, such as the methods illustrated by the flowchart of  FIGS.  2 - 4   . In other embodiments, different elements and data may be included. 
     Those skilled in the art will appreciate that computer system  500  is merely illustrative and is not intended to limit the scope of embodiments. In particular, the computer system and devices may include any combination of hardware or software that can perform the indicated functions of various embodiments, including computers, network devices, Internet appliances, PDAs, wireless phones, pagers, and the like. Computer system  500  may also be connected to other devices that are not illustrated, or instead may operate as a stand-alone system. In addition, the functionality provided by the illustrated components may in some embodiments be combined in fewer components or distributed in additional components. Similarly, in some embodiments, the functionality of some of the illustrated components may not be provided and/or other additional functionality may be available. 
     Those skilled in the art will also appreciate that, while various items are illustrated as being stored in memory or on storage while being used, these items or portions of them may be transferred between memory and other storage devices for purposes of memory management and data integrity. Alternatively, in other embodiments some or all of the software components may execute in memory on another device and communicate with the illustrated computer system via inter-computer communication. Some or all of the system components or data structures may also be stored (e.g., as instructions or structured data) on a computer-accessible medium or a portable article to be read by an appropriate drive, various examples of which are described above. In some embodiments, instructions stored on a computer-accessible medium separate from computer system  500  may be transmitted to computer system  500  via transmission media or signals such as electrical, electromagnetic, or digital signals, conveyed via a communication medium such as a network and/or a wireless link. Various embodiments may further include receiving, sending or storing instructions and/or data implemented in accordance with the foregoing description upon a computer-accessible medium or via a communication medium. In general, a computer-accessible medium may include a storage medium or memory medium such as magnetic or optical media, e.g., disk or DVD/CD-ROM, volatile or non-volatile media such as RAM (e.g., SDRAM, DDR, RDRAM, SRAM, and the like), ROM, and the like. 
     The methods described herein may be implemented in software, hardware, or a combination thereof, in different embodiments. In addition, the order of methods may be changed, and various elements may be added, reordered, combined, omitted or otherwise modified. All examples described herein are presented in a non-limiting manner. Various modifications and changes may be made as would be obvious to a person skilled in the art having benefit of this disclosure. Realizations in accordance with embodiments have been described in the context of particular embodiments. These embodiments are meant to be illustrative and not limiting. Many variations, modifications, additions, and improvements are possible. Accordingly, plural instances may be provided for components described herein as a single instance. Boundaries between various components, operations and data stores are somewhat arbitrary, and particular operations are illustrated in the context of specific illustrative configurations. Other allocations of functionality are envisioned and may fall within the scope of claims that follow. Finally, structures and functionality presented as discrete components in the example configurations may be implemented as a combined structure or component. These and other variations, modifications, additions, and improvements may fall within the scope of embodiments as defined in the claims that follow. 
     In the foregoing description, numerous specific details, examples, and scenarios are set forth in order to provide a more thorough understanding of the present disclosure. It will be appreciated, however, that embodiments of the disclosure may be practiced without such specific details. Further, such examples and scenarios are provided for illustration, and are not intended to limit the disclosure in any way. Those of ordinary skill in the art, with the included descriptions, should be able to implement appropriate functionality without undue experimentation. 
     References in the specification to “an embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is believed to be within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly indicated. 
     Embodiments in accordance with the disclosure may be implemented in hardware, firmware, software, or any combination thereof. Embodiments may also be implemented as instructions stored using one or more machine-readable media, which may be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device or a “virtual machine” running on one or more computing devices). For example, a machine-readable medium may include any suitable form of volatile or non-volatile memory. 
     Modules, data structures, and the like defined herein are defined as such for ease of discussion and are not intended to imply that any specific implementation details are required. For example, any of the described modules and/or data structures may be combined or divided into sub-modules, sub-processes or other units of computer code or data as may be required by a particular design or implementation. 
     In the drawings, specific arrangements or orderings of schematic elements may be shown for ease of description. However, the specific ordering or arrangement of such elements is not meant to imply that a particular order or sequence of processing, or separation of processes, is required in all embodiments. In general, schematic elements used to represent instruction blocks or modules may be implemented using any suitable form of machine-readable instruction, and each such instruction may be implemented using any suitable programming language, library, application-programming interface (API), and/or other software development tools or frameworks. Similarly, schematic elements used to represent data or information may be implemented using any suitable electronic arrangement or data structure. Further, some connections, relationships or associations between elements may be simplified or not shown in the drawings so as not to obscure the disclosure.