Detection: Analyze network data for uncommon data flows (e.g., a client sending significantly more data than it receives from a server). Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious. Analyze packet contents to detect communications that do not follow the expected protocol behavior for the port that is being used. (Citation: University of Birmingham C2)

Data exfiltration is performed with a different protocol from the main command and control protocol or channel. The data is likely to be sent to an alternate network location from the main command and control server. Alternate protocols include FTP, SMTP, HTTP/S, DNS, or some other network protocol. Different channels could include Internet Web services such as cloud storage.

Detection: Analyze network data for uncommon data flows (e.g., a client sending significantly more data than it receives from a server). Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious. Analyze packet contents to detect application layer protocols that do not follow the expected protocol for the port that is being used. (Citation: University of Birmingham C2)

For connections that occur internally within an enclave (such as those between a proxy or pivot node and other nodes), commonly used protocols are RPC, SSH, or RDP.

Adversaries may communicate using a common, standardized application layer protocol such as HTTP, HTTPS, SMTP, or DNS to avoid detection by blending in with existing traffic. Commands to the remote system, and often the results of those commands, will be embedded within the protocol traffic between the client and server.

Adversaries can perform command and control between compromised hosts on potentially disconnected networks using removable media to transfer commands from system to system. Both systems would need to be compromised, with the likelihood that an Internet-connected system was compromised first and the second through lateral movement by Replication Through Removable Media. Commands and files would be relayed from the disconnected system to the Internet-connected system to which the adversary has direct access.

The user access logging within Microsoft’s SharePoint can be configured to report access to certain pages and documents. (Citation: Microsoft SharePoint Logging) The user user access logging within Atlassian’s Confluence can also be configured to report access to certain pages and documents through AccessLogFilter. (Citation: Atlassian Confluence Logging) Additional log storage and analysis infrastructure will likely be required for more robust detection capabilities.

Detection: As information repositories generally have a considerably large user base, detection of malicious use can be non-trivial. At minimum, access to information repositories performed by privileged users (for example, Active Directory Domain, Enterprise, or Schema Administrators) should be closely monitored and alerted upon, as these types of accounts should not generally used to access information repositories. If the capability exists, it may be of value to monitor and alert on users that are retrieving and viewing a large number of documents and pages; this behavior may be indicative of programmatic means being used to retrieve all data within the repository. In environments with high-maturity, it may be possible to leverage User-Behavioral Analytics (UBA) platforms to detect and alert on user based anomalies.

===Microsoft SharePoint=== Found in many enterprise networks and often used to store and share significant amounts of documentation.

The following is a brief list of example information that may hold potential value to an adversary and may also be found on an information repository:

Adversaries may leverage information repositories to mine valuable information. Information repositories are tools that allow for storage of information, typically to facilitate collaboration or information sharing between users, and can store a wide variety of data that may aid adversaries in further objectives, or direct access to the target information.

Tools such as Sysinternals Autoruns can be used to detect changes to the screensaver binary path in the Registry. Suspicious paths and PE files may indicate outliers among legitimate screensavers in a network and should be investigated.

Detection: Monitor process execution and command-line parameters of .scr files. Monitor changes to screensaver configuration changes in the Registry that may not correlate with typical user behavior.

Adversaries can use screensaver settings to maintain persistence by setting the screensaver to run malware after a certain timeframe of user inactivity. (Citation: ESET Gazer Aug 2017)

*<code>SCRNSAVE.exe</code> - set to malicious PE path *<code>ScreenSaveActive</code> - set to '1' to enable the screensaver *<code>ScreenSaverIsSecure</code> - set to '0' to not require a password to unlock *<code>ScreenSaverTimeout</code> - sets user inactivity timeout before screensaver is executed

Screensavers are programs that execute after a configurable time of user inactivity and consist of Portable Executable (PE) files with a .scr file extension. (Citation: Wikipedia Screensaver) The Windows screensaver application scrnsave.exe is located in <code>C:\Windows\System32\</code> along with screensavers included with base Windows installations. The following screensaver settings are stored in the Registry (<code>HKCU\Control Panel\Desktop\</code>) and could be manipulated to achieve persistence:

Detection: Monitor processes for tools and command line arguments that may indicate they’re being used for password policy discovery. Correlate that activity with other suspicious activity from the originating system to reduce potential false positives from valid user or administrator activity. Adversaries will likely attempt to find the password policy early in an operation and the activity is likely to happen with other Discovery activity.

Password policies for networks are a way to enforce complex passwords that are difficult to guess or crack through Brute Force. An adversary may attempt to access detailed information about the password policy used within an enterprise network. This would help the adversary to create a list of common passwords and launch dictionary and/or brute force attacks which adheres to the policy (e.g. if the minimum password length should be 8, then not trying passwords such as 'pass123'; not checking for more than 3-4 passwords per account if the lockout is set to 6 as to not lock out accounts).

Detection: Analyze network data for uncommon data flows (e.g., a client sending significantly more data than it receives from a server). Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious. Analyze packet contents to detect communications that do not follow the expected protocol behavior for the port that is being used. (Citation: University of Birmingham C2)

Adversaries may communicate using a custom command and control protocol instead of using existing Standard Application Layer Protocol to encapsulate commands. Implementations could mimic well-known protocols.

Look for abnormal process call trees from typical processes and services and for execution of other commands that could relate to Discovery or other adversary techniques.

Detection: Look for changes to binaries and service executables that may normally occur during software updates. If an executable is written, renamed, and/or moved to match an existing service executable, it could be detected and correlated with other suspicious behavior. Hashing of binaries and service executables could be used to detect replacement against historical data.

Another variation of this technique can be performed by taking advantage of a weakness that is common in executable, self-extracting installers. During the installation process, it is common for installers to use a subdirectory within the <code>%TEMP%</code> directory to unpack binaries such as DLLs, EXEs, or other payloads. When installers create subdirectories and files they often do not set appropriate permissions to restrict write access, which allows for execution of untrusted code placed in the subdirectories or overwriting of binaries used in the installation process. This behavior is related to and may take advantage of DLL Search Order Hijacking. Some installers may also require elevated privileges that will result in privilege escalation when executing adversary controlled code. This behavior is related to Bypass User Account Control. Several examples of this weakness in existing common installers have been reported to software vendors. (Citation: Mozilla Firefox Installer DLL Hijack) (Citation: Seclists Kanthak 7zip Installer)

Manipulation of Windows service binaries is one variation of this technique. Adversaries may replace a legitimate service executable with their own executable to gain persistence and/or privilege escalation to the account context the service is set to execute under (local/domain account, SYSTEM, LocalService, or NetworkService). Once the service is started, either directly by the user (if appropriate access is available) or through some other means, such as a system restart if the service starts on bootup, the replaced executable will run instead of the original service executable.

Adversaries may use this technique to replace legitimate binaries with malicious ones as a means of executing code at a higher permissions level. If the executing process is set to run at a specific time or during a certain event (e.g., system bootup) then this technique can also be used for persistence.

Processes may automatically execute specific binaries as part of their functionality or to perform other actions. If the permissions on the file system directory containing a target binary, or permissions on the binary itself, are improperly set, then the target binary may be overwritten with another binary using user-level permissions and executed by the original process. If the original process and thread are running under a higher permissions level, then the replaced binary will also execute under higher-level permissions, which could include SYSTEM.

Analyze process behavior to determine if a process is performing actions it usually does not, such as opening network connections, reading files, or other suspicious actions that could relate to post-compromise behavior.

Detection: Monitoring API calls may generate a significant amount of data and may not be directly useful for defense unless collected under specific circumstances for known bad sequences of calls, since benign use of API functions may be common and difficult to distinguish from malicious behavior. API calls that unmap process memory, such as ZwUnmapViewOfSection or NtUnmapViewOfSection, and those that can be used to modify memory within another process, such as WriteProcessMemory, may be used for this technique. (Citation: Engame Process Injection July 2017)

Process hollowing occurs when a process is created in a suspended state then its memory is unmapped and replaced with malicious code. Similar to Process Injection, execution of the malicious code is masked under a legitimate process and may evade defenses and detection analysis. (Citation: Leitch Hollowing) (Citation: Engame Process Injection July 2017)

Analyze Office file attachments for potentially malicious macros. Execution of macros may create suspicious process trees depending on what the macro is designed to do. Office processes, such as word.exe, spawning instances of cmd.exe, script application like wscript.exe or powershell.exe, or other suspicious processes may indicate malicious activity. (Citation: Uperesia Malicious Office Documents)

Scripts are likely to perform actions with various effects on a system that may generate events, depending on the types of monitoring used. Monitor processes and command-line arguments for script execution and subsequent behavior. Actions may be related to network and system information Discovery, Collection, or other scriptable post-compromise behaviors and could be used as indicators of detection leading back to the source script.

Detection: Scripting may be common on admin, developer, or power user systems, depending on job function. If scripting is restricted for normal users, then any attempts to enable scripts running on a system would be considered suspicious. If scripts are not commonly used on a system, but enabled, scripts running out of cycle from patching or other administrator functions are suspicious. Scripts should be captured from the file system when possible to determine their actions and intent.

Many popular offensive frameworks exist which use forms of scripting for security testers and adversaries alike. (Citation: Metasploit) (Citation: Metasploit), (Citation: Veil) (Citation: Veil), and PowerSploit (Citation: Powersploit) are three examples that are popular among penetration testers for exploit and post-compromise operations and include many features for evading defenses. Some adversaries are known to use PowerShell. (Citation: Alperovitch 2014)

Scripts can be embedded inside Office documents as macros that can be set to execute when files used in Spearphishing Attachment and other types of spearphishing are opened. Malicious embedded macros are an alternative means of execution than software exploitation through Exploitation for Client Execution, where adversaries will rely on macos being allowed or that the user will accept to activate them.

Adversaries may use scripts to aid in operations and perform multiple actions that would otherwise be manual. Scripting is useful for speeding up operational tasks and reducing the time required to gain access to critical resources. Some scripting languages may be used to bypass process monitoring mechanisms by directly interacting with the operating system at an API level instead of calling other programs. Common scripting languages for Windows include VBScript and PowerShell but could also be in the form of command-line batch scripts.

Detection: Monitor for execution of AppleScript through osascript that may be related to other suspicious behavior occurring on the system.

Adversaries can use this to interact with open SSH connection, move to remote machines, and even present users with fake dialog boxes. These events cannot start applications remotely (they can start them locally though), but can interact with applications if they’re already running remotely. Since this is a scripting language, it can be used to launch more common techniques as well such as a reverse shell via python (Citation: Macro Malware Targets Macs). Scripts can be run from the command lie via <code>osascript /path/to/script</code> or <code>osascript -e "script here"</code>.

macOS and OS X applications send AppleEvent messages to each other for interprocess communications (IPC). These messages can be easily scripted with AppleScript for local or remote IPC. Osascript executes AppleScript and any other Open Scripting Architecture (OSA) language scripts. A list of OSA languages installed on a system can be found by using the <code>osalang</code> program. AppleEvent messages can be sent independently or as part of a script. These events can locate open windows, send keystrokes, and interact with almost any open application locally or remotely.

Detection: Monitor processes and command-line arguments for actions that could be taken to collect files from a system’s connected removable media. Remote access tools with built-in features may interact directly with the Windows API to gather data. Data may also be acquired through Windows system management tools such as Windows Management Instrumentation and PowerShell.

Adversaries may search connected removable media on computers they have compromised to find files of interest. Interactive command shells may be in use, and common functionality within cmd may be used to gather information. Some adversaries may also use Automated Collection on removable media.

Sensitive data can be collected from any removable media (optical disk drive, USB memory, etc.) connected to the compromised system prior to Exfiltration.

Detection: Collect and analyze signing certificate metadata on software that executes within the environment to look for unusual certificate characteristics and outliers.

Code signing certificates may be used to bypass security policies that require signed code to execute on a system.

Code signing to verify software on first run can be used on modern Windows and macOS/OS X systems. It is not used on Linux due to the decentralized nature of the platform. (Citation: Wikipedia Code Signing)

Code signing provides a level of authenticity on a binary from the developer and a guarantee that the binary has not been tampered with. (Citation: Wikipedia Code Signing) However, adversaries are known to use code signing certificates to masquerade malware and tools as legitimate binaries (Citation: Janicab). The certificates used during an operation may be created, forged, or stolen by the adversary. (Citation: Securelist Digital Certificates) (Citation: Symantec Digital Certificates)

Look for abnormal process behavior that may be due to a process loading a malicious DLL. Data and events should not be viewed in isolation, but as part of a chain of behavior that could lead to other activities, such as making network connections for Command and Control, learning details about the environment through Discovery, and conducting Lateral Movement.

Detection: Monitor DLL loads by processes, specifically looking for DLLs that are not recognized or not normally loaded into a process. Monitor the AppCertDLLs Registry value for modifications that do not correlate with known software, patch cycles, etc. Monitor and analyze application programming interface (API) calls that are indicative of Registry edits such as RegCreateKeyEx and RegSetValueEx. (Citation: Engame Process Injection July 2017)

Dynamic-link libraries (DLLs) that are specified in the AppCertDLLs value in the Registry key <code>HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Session Manager</code> are loaded into every process that calls the ubiquitously used application programming interface (API) functions: (Citation: Engame Process Injection July 2017) *CreateProcess *CreateProcessAsUser *CreateProcessWithLoginW *CreateProcessWithTokenW *WinExec Similar to Process Injection, this value can be abused to obtain persistence and privilege escalation by causing a malicious DLL to be loaded and run in the context of separate processes on the computer.

Detection: Some rootkit protections may be built into anti-virus or operating system software. There are dedicated rootkit detection tools that look for specific types of rootkit behavior. Monitor for the existence of unrecognized DLLs, devices, services, and changes to the MBR. (Citation: Wikipedia Rootkit)

Adversaries may use rootkits to hide the presence of programs, files, network connections, services, drivers, and other system components. Rootkits have been seen for Windows, Linux, and Mac OS X systems. (Citation: CrowdStrike Linux Rootkit) (Citation: BlackHat Mac OSX Rootkit)

Rootkits are programs that hide the existence of malware by intercepting (i.e., Hooking) and modifying operating system API calls that supply system information. (Citation: Symantec Windows Rootkits) Rootkits or rootkit enabling functionality may reside at the user or kernel level in the operating system or lower, to include a Hypervisor, Master Boot Record, or the System Firmware. (Citation: Wikipedia Rootkit)

Detection: All the login items are viewable by going to the Apple menu → System Preferences → Users & Groups → Login items. This area should be monitored and whitelisted for known good applications. Monitor process execution resulting from login actions for unusual or unknown applications.

MacOS provides the option to list specific applications to run when a user logs in. These applications run under the logged in user’s context, and will be started every time the user logs in. Login items installed using the Service Management Framework are not visible in the System Preferences and can only be removed by the application that created them (Citation: Adding Login Items). Users have direct control over login items installed using a shared file list which are also visible in System Preferences (Citation: Adding Login Items). These login items are stored in the user’s <code>~/Library/Preferences/</code> directory in a plist file called <code>com.apple.loginitems.plist</code> (Citation: Methods of Mac Malware Persistence). Some of these applications can open visible dialogs to the user, but they don’t all have to since there is an option to ‘Hide’ the window. If an adversary can register their own login item or modified an existing one, then they can use it to execute their code for a persistence mechanism each time the user logs in (Citation: Malware Persistence on OS X) (Citation: OSX.Dok Malware).

Detection: Command-line interface activities can be captured through proper logging of process execution with command-line arguments. This information can be useful in gaining additional insight to adversaries' actions through how they use native processes or custom tools.

Adversaries may use command-line interfaces to interact with systems and execute other software during the course of an operation.

Command-line interfaces provide a way of interacting with computer systems and is a common feature across many types of operating system platforms. (Citation: Wikipedia Command-Line Interface) One example command-line interface on Windows systems is cmd, which can be used to perform a number of tasks including execution of other software. Command-line interfaces can be interacted with locally or remotely via a remote desktop application, reverse shell session, etc. Commands that are executed run with the current permission level of the command-line interface process unless the command includes process invocation that changes permissions context for that execution (e.g. Scheduled Task).

Detection: Detection for command and control applies. Analyze network data for uncommon data flows (e.g., a client sending significantly more data than it receives from a server). Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious. Analyze packet contents to detect communications that do not follow the expected protocol behavior for the port that is being used. (Citation: University of Birmingham C2)

Data exfiltration is performed over the Command and Control channel. Data is encoded into the normal communications channel using the same protocol as command and control communications.

Anti-virus can potentially detect malicious documents and files that are downloaded and execuited on the user’s computer. Endpoint sensing or network sensing can potentially detect malicious events once the file is opened (such as a Microsoft Word document or PDF reaching out to the internet or spawning Powershell.exe) for techniques such as Exploitation for Client Execution and Scripting.

Detection: Monitor the execution of and command-line arguments for applications that may be used by an adversary to gain Initial Access that require user interaction. This includes compression applications, such as those for zip files, that can be used to Deobfuscate/Decode Files or Information in payloads.

An adversary may rely upon specific actions by a user in order to gain execution. This may be direct code execution, such as when a user opens a malicious executable delivered via Spearphishing Attachment with the icon and apparent extension of a document file. It also may lead to other execution techniques, such as when a user clicks on a link delivered via Spearphishing Link that leads to exploitation of a browser or application vulnerability via Exploitation for Client Execution. While User Execution frequently occurs shortly after Initial Access it may occur at other phases of an intrusion, such as when an adversary places a file in a shared directory or on a user’s desktop hoping that a user will click on it.

Detection: Host data that can relate unknown or suspicious process activity using a network connection is important to supplement any existing indicators of compromise based on malware command and control signatures and infrastructure. Relating subsequent actions that may result from Discovery of the system and network information or Lateral Movement to the originating process may also yield useful data.

The different stages will likely be hosted separately with no overlapping infrastructure. The loader may also have backup first-stage callbacks or Fallback Channels in case the original first-stage communication path is discovered and blocked.

Remote access tools will call back to the first-stage command and control server for instructions. The first stage may have automated capabilities to collect basic host information, update tools, and upload additional files. A second remote access tool (RAT) could be uploaded at that point to redirect the host to the second-stage command and control server. The second stage will likely be more fully featured and allow the adversary to interact with the system through a reverse shell and additional RAT features.

Adversaries may create multiple stages for command and control that are employed under different conditions or for certain functions. Use of multiple stages may obfuscate the command and control channel to make detection more difficult.

If an adversary can obtain root access (allowing them to read securityd’s memory), then they can scan through memory to find the correct sequence of keys in relatively few tries to decrypt the user’s logon keychain. This provides the adversary with all the plaintext passwords for users, WiFi, mail, browsers, certificates, secure notes, etc. (Citation: OS X Keychain) (Citation: OSX Keydnap malware)

In OS X prior to El Capitan, users with root access can read plaintext keychain passwords of logged-in users because Apple’s keychain implementation allows these credentials to be cached so that users are not repeatedly prompted for passwords. (Citation: OS X Keychain) (Citation: External to DA, the OS X Way) Apple’s securityd utility takes the user’s logon password, encrypts it with PBKDF2, and stores this master key in memory. Apple also uses a set of keys and algorithms to encrypt the user’s password, but once the master key is found, an attacker need only iterate over the other values to unlock the final password. (Citation: OS X Keychain)

Anti-virus can potentially detect malicious documents and attachments as they’re scanned to be stored on the email server or on the user’s computer. Endpoint sensing or network sensing can potentially detect malicious events once the attachment is opened (such as a Microsoft Word document or PDF reaching out to the internet or spawning Powershell.exe) for techniques such as Exploitation for Client Execution and Scripting.

Detection: Network intrusion detection systems and email gateways can be used to detect spearphishing with malicious attachments in transit. Detonation chambers may also be used to identify malicious attachments. Solutions can be signature and behavior based, but adversaries may construct attachments in a way to avoid these systems.

There are many options for the attachment such as Microsoft Office documents, executables, PDFs, or archived files. Upon opening the attachment (and potentially clicking past protections), the adversary’s payload exploits a vulnerability or directly executes on the user’s system. The text of the spearphishing email usually tries to give a plausible reason why the file should be opened, and may explain how to bypass system protections in order to do so. The email may also contain instructions on how to decrypt an attachment, such as a zip file password, in order to evade email boundary defenses. adversaries frequently manipulate file extensions and icons in order to make attached executables appear to be document files, or files exploiting one application appear to be a file for a different one.

Spearphishing attachment is a specific variant of spearphishing. Spearphishing attachment is different from other forms of spearphishing in that it employs the use of malware attached to an email. All forms of spearphishing are electronically delivered social engineering targeted at a specific individual, company, or industry. In this scenario, adversaries attach a file to the spearphishing email and usually rely upon User Execution to gain execution.

Detection: There are several public tools available that will detect shims that are currently available (Citation: Black Hat 2015 App Shim):

To keep shims secure, Windows designed them to run in user mode so they cannot modify the kernel and you must have administrator privileges to install a shim. However, certain shims can be used to Bypass User Account Control (UAC) (RedirectEXE), inject DLLs into processes (InjectDLL), disable Data Execution Prevention (DisableNX) and Structure Exception Handling (DisableSEH), and intercept memory addresses (GetProcAddress). Similar to Hooking, utilizing these shims may allow an adversary to perform several malicious acts such as elevate privileges, install backdoors, disable defenses like Windows Defender, etc.

The Microsoft Windows Application Compatibility Infrastructure/Framework (Application Shim) was created to allow backward compatibility of programs as Windows updates and changes its code. For example, the application shimming feature allows developers to apply fixes to applications (without rewriting code) that were created for Windows XP so that it will work with Windows 10. (Citation: Engame Process Injection July 2017) Within the framework, shims are created to act as a buffer between the program (or more specifically, the Import Address Table) and the Windows OS. When a program is executed, the shim cache is referenced to determine if the program requires the use of the shim database (.sdb). If so, the shim database uses Hooking to redirect the code as necessary in order to communicate with the OS. A list of all shims currently installed by the default Windows installer (sdbinst.exe) is kept in:

Monitor the Registry for the addition of a Custom Credential Provider. (Citation: Wrightson 2012) Detection of compromised Valid Accounts in use by adversaries may help to catch the result of user input interception if new techniques are used.

Detection: Keyloggers may take many forms, possibly involving modification to the Registry and installation of a driver, setting a hook, or polling to intercept keystrokes. Commonly used API calls include SetWindowsHook, GetKeyState, and GetAsynceyState. (Citation: Adventures of a Keystroke) Monitor the Registry and file system for such changes and detect driver installs, as well as looking for common keylogging API calls. API calls alone are not an indicator of keylogging, but may provide behavioral data that is useful when combined with other information such as new files written to disk and unusual processes.

Adversaries may also install code on externally facing portals, such as a VPN login page, to capture and transmit credentials of users who attempt to log into the service. This variation on input capture may be conducted post-compromise using legitimate administrative access as a backup measure to maintain network access through External Remote Services and Valid Accounts or as part of the initial compromise by exploitation of the externally facing web service. (Citation: Volexity Virtual Private Keylogging)

Keylogging is likely to be used to acquire credentials for new access opportunities when Credential Dumping efforts are not effective, and may require an adversary to remain passive on a system for a period of time before an opportunity arises.

Keylogging is the most prevalent type of input capture, with many different ways of intercepting keystrokes, (Citation: Adventures of a Keystroke) but other methods exist to target information for specific purposes, such as performing a UAC prompt or wrapping the Windows default credential provider. (Citation: Wrightson 2012)

Adversaries can use methods of capturing user input for obtaining credentials for Valid Accounts and information Collection that include keylogging and user input field interception.

Detection: Use process monitoring to monitor the execution and arguments of Regsvcs.exe and Regasm.exe. Compare recent invocations of Regsvcs.exe and Regasm.exe with prior history of known good arguments and executed binaries to determine anomalous and potentially adversarial activity. Command arguments used before and after Regsvcs.exe or Regasm.exe invocation may also be useful in determining the origin and purpose of the binary being executed.

Adversaries can use Regsvcs and Regasm to proxy execution of code through a trusted Windows utility. Both utilities may be used to bypass process whitelisting through use of attributes within the binary to specify code that should be run before registration or unregistration: <code>[ComRegisterFunction]</code> or <code>[ComUnregisterFunction]</code> respectively. The code with the registration and unregistration attributes will be executed even if the process is run under insufficient privileges and fails to execute. (Citation: SubTee GitHub All The Things Application Whitelisting Bypass)

Regsvcs and Regasm are Windows command-line utilities that are used to register .NET Component Object Model (COM) assemblies. Both are digitally signed by Microsoft. (Citation: MSDN Regsvcs) (Citation: MSDN Regasm)

Use process monitoring to monitor the execution and arguments of MSBuild.exe, dnx.exe, rcsi.exe, WinDbg.exe, cdb.exe, and tracker.exe. Compare recent invocations of those binaries with prior history of known good arguments and executed binaries to determine anomalous and potentially adversarial activity. It is likely that these utilities will be used by software developers or for other software development related tasks, so if it exists and is used outside of that context, then the event may be suspicious. Command arguments used before and after invocation of the utilities may also be useful in determining the origin and purpose of the binary being executed.

Detection: The presence of these or other utilities that enable proxy execution that are typically used for development, debugging, and reverse engineering on a system that is not used for these purposes may be suspicious.

An adversary can use tracker.exe to proxy execution of an arbitrary DLL into another process. Since tracker.exe is also signed it can be used to bypass application whitelisting solutions. (Citation: Twitter SubTee Tracker.exe)

The file tracker utility, tracker.exe, is included with the .NET framework as part of MSBuild. It is used for logging calls to the Windows file system. (Citation: Microsoft Docs File Tracking)

It is likely possible to use other debuggers for similar purposes, such as the kernel-mode debugger kd.exe, which is also signed by Microsoft.

An adversary can use WinDbg.exe and cdb.exe to proxy execution of arbitrary code to bypass application whitelist policies that do not account for execution of those utilities. (Citation: Exploit Monday WinDbg)

WinDbg is a Microsoft Windows kernel and user-mode debugging utility. The Microsoft Console Debugger (CDB) cdb.exe is also user-mode debugger. Both utilities are included in Windows software development kits and can be used as standalone tools. (Citation: Microsoft Debugging Tools for Windows) They are commonly used in software development and reverse engineering and may not be found on typical Windows systems. Both WinDbg.exe and cdb.exe binaries are signed by Microsoft.

C# .csx script files can be written and executed with rcsi.exe at the command-line. An adversary can use rcsi.exe to proxy execution of arbitrary code to bypass application whitelisting policies that do not account for execution of rcsi.exe. (Citation: engima0x3 RCSI Bypass)

The rcsi.exe utility is a non-interactive command-line interface for C# that is similar to csi.exe. It was provided within an early version of the Roslyn .NET Compiler Platform but has since been deprecated for an integrated solution. (Citation: Microsoft Roslyn CPT RCSI) The rcsi.exe binary is signed by Microsoft. (Citation: engima0x3 RCSI Bypass)

An adversary can use dnx.exe to proxy execution of arbitrary code to bypass application whitelist policies that do not account for DNX. (Citation: engima0x3 DNX Bypass)

The .NET Execution Environment (DNX), dnx.exe, is a software development kit packaged with Visual Studio Enterprise. It was retired in favor of .NET Core CLI in 2016. (Citation: Microsoft Migrating from DNX) DNX is not present on standard builds of Windows and may only be present on developer workstations using older versions of .NET Core and ASP.NET Core 1.0. The dnx.exe executable is signed by Microsoft.

Adversaries can use MSBuild to proxy execution of code through a trusted Windows utility. The inline task capability of MSBuild that was introduced in .NET version 4 allows for C# code to be inserted into the XML project file. (Citation: MSDN MSBuild) Inline Tasks MSBuild will compile and execute the inline task. MSBuild.exe is a signed Microsoft binary, so when it is used this way it can execute arbitrary code and bypass application whitelisting defenses that are configured to allow MSBuild.exe execution. (Citation: SubTee GitHub All The Things Application Whitelisting Bypass)

MSBuild.exe (Microsoft Build Engine) is a software build platform used by Visual Studio. It takes XML formatted project files that define requirements for building various platforms and configurations. (Citation: MSDN MSBuild)

There are many utilities used for software development related tasks that can be used to execute code in various forms to assist in development, debugging, and reverse engineering. These utilities may often be signed with legitimate certificates that allow them to execute on a system and proxy execution of malicious code through a trusted process that effectively bypasses application whitelisting defensive solutions.

Monitor processes and command-line arguments for actions that could be taken to gather system and network information. Remote access tools with built-in features may interact directly with the Windows API to gather information. Information may also be acquired through Windows system management tools such as Windows Management Instrumentation and PowerShell.

Detection: System and network discovery techniques normally occur throughout an operation as an adversary learns the environment. Data and events should not be viewed in isolation, but as part of a chain of behavior that could lead to other activities, such as Lateral Movement, based on the information obtained.

Adversaries will likely look for details about the network configuration and settings of systems they access or through information discovery of remote systems. Several operating system administration utilities exist that can be used to gather this information. Examples include Arp, ipconfig/ifconfig, nbtstat, and route.

Monitor processes and command-line arguments for actions that could be taken to create tasks. Remote access tools with built-in features may interact directly with the Windows API to perform these functions outside of typical system utilities. Tasks may also be created through Windows system management tools such as Windows Management Instrumentation and PowerShell, so additional logging may need to be configured to gather the appropriate data.

Tools such as Sysinternals Autoruns may also be used to detect system changes that could be attempts at persistence, including listing current scheduled tasks. (Citation: TechNet Autoruns) Look for changes to tasks that do not correlate with known software, patch cycles, etc. Suspicious program execution through scheduled tasks may show up as outlier processes that have not been seen before when compared against historical data.

Configure event logging for scheduled task creation and changes by enabling the "Microsoft-Windows-TaskScheduler/Operational" setting within the event logging service. (Citation: TechNet Forum Scheduled Task Operational Setting) Several events will then be logged on scheduled task activity, including: (Citation: TechNet Scheduled Task Events)

Detection: Monitor scheduled task creation from common utilities using command-line invocation. Legitimate scheduled tasks may be created during installation of new software or through system administration functions. Monitor process execution from the <code>svchost.exe</code> in Windows 10 and the Windows Task Scheduler <code>taskeng.exe</code> for older versions of Windows. (Citation: Twitter Leoloobeek Scheduled Task) If scheduled tasks are not used for persistence, then the adversary is likely to remove the task when the action is complete. Monitor Windows Task Scheduler stores in <code>%systemroot%\System32\Tasks</code> for change entries related to scheduled tasks that do not correlate with known software, patch cycles, etc. Data and events should not be viewed in isolation, but as part of a chain of behavior that could lead to other activities, such as network connections made for Command and Control, learning details about the environment through Discovery, and Lateral Movement.

An adversary may use task scheduling to execute programs at system startup or on a scheduled basis for persistence, to conduct remote Execution as part of Lateral Movement, to gain SYSTEM privileges, or to run a process under the context of a specified account.

Utilities such as at and schtasks, along with the Windows Task Scheduler, can be used to schedule programs or scripts to be executed at a date and time. A task can also be scheduled on a remote system, provided the proper authentication is met to use RPC and file and printer sharing is turned on. Scheduling a task on a remote system typically required being a member of the Administrators group on the the remote system. (Citation: TechNet Task Scheduler Security)

Detection: Trap commands must be registered for the shell or programs, so they appear in files. Monitoring files for suspicious or overly broad trap commands can narrow down suspicious behavior during an investigation. Monitor for suspicious processes executed through trap interrupts.

The <code>trap</code> command allows programs and shells to specify commands that will be executed upon receiving interrupt signals. A common situation is a script allowing for graceful termination and handling of common keyboard interrupts like <code>ctrl+c</code> and <code>ctrl+d</code>. Adversaries can use this to register code to be executed when the shell encounters specific interrupts either to gain execution or as a persistence mechanism. Trap commands are of the following format <code>trap 'command list' signals</code> where "command list" will be executed when "signals" are received.

Detection: Monitor network traffic for WMI connections; the use of WMI in environments that do not typically use WMI may be suspect. Perform process monitoring to capture command-line arguments of "wmic" and detect commands that are used to perform remote behavior. (Citation: FireEye WMI 2015)

An adversary can use WMI to interact with local and remote systems and use it as a means to perform many tactic functions, such as gathering information for Discovery and remote Execution of files as part of Lateral Movement. (Citation: FireEye WMI 2015)

Windows Management Instrumentation (WMI) is a Windows administration feature that provides a uniform environment for local and remote access to Windows system components. It relies on the WMI service for local and remote access and the server message block (SMB) (Citation: Wikipedia SMB) and Remote Procedure Call Service (RPCS) (Citation: TechNet RPC) for remote access. RPCS operates over port 135. (Citation: MSDN WMI)

Monitor for operations (execution, copies, etc.) with file names that contain colons. This syntax (ex: <code>file.ext:ads[.ext]</code>) is commonly associated with ADSs. (Citation: Microsoft ADS Mar 2014)

The Streams tool of Sysinternals can be used to uncover files with ADSs. The <code>dir /r</code> command can also be used to display ADSs. (Citation: Symantec ADS May 2009) Many PowerShell commands (such as Get-Item, Set-Item, Remove-Item, and Get-ChildItem) can also accept a <code>-stream</code> parameter to interact with ADSs. (Citation: MalwareBytes ADS July 2015) (Citation: Microsoft ADS Mar 2014)

Detection: Forensic techniques exist to identify information stored in NTFS EA. (Citation: Journey into IR ZeroAccess NTFS EA) Monitor calls to the ZwSetEaFile and ZwQueryEaFile Windows API functions, used to interact with EA, and consider regularly scanning for the presence of modified information. (Citation: SpectorOps Host-Based Jul 2017)

Adversaries may store malicious data or binaries in file attribute metadata instead of directly in files. This may be done to evade some defenses, such as static indicator scanning tools and anti-virus. (Citation: Journey into IR ZeroAccess NTFS EA) (Citation: MalwareBytes ADS July 2015)

Every New Technology File System (NTFS) formatted partition contains a Master File Table (MFT) that maintains a record for every file/directory on the partition. (Citation: SpectorOps Host-Based Jul 2017) Within MFT entries are file attributes, (Citation: Microsoft NTFS File Attributes Aug 2010) such as Extended Attributes (EA) and Data [known as Alternative Data Streams (ADSs) when more than one Data attribute is present], that can be used to store arbitrary data (and even complete files). (Citation: SpectorOps Host-Based Jul 2017) (Citation: Microsoft File Streams) (Citation: MalwareBytes ADS July 2015) (Citation: Microsoft ADS Mar 2014)

Domain Fronting may be used in conjunction to avoid defenses. Adversaries will likely need to deploy and/or install these remote tools to compromised systems. It may be possible to detect or prevent the installation of these tools with host-based solutions.

Analyze network data for uncommon data flows (e.g., a client sending significantly more data than it receives from a server). Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious. Analyze packet contents to detect application layer protocols that do not follow the expected protocol for the port that is being used.

Detection: Monitor for applications and processes related to remote admin tools. Correlate activity with other suspicious behavior that may reduce false positives if these tools are used by legitimate users and administrators.

Admin tools such as TeamViewer have been used by several groups targeting institutions in countries of interest to the Russian state and criminal campaigns. (Citation: CrowdStrike 2015 Global Threat Report) (Citation: CrySyS Blog TeamSpy)

Remote access tools may be established and used post-compromise as alternate communications channel for Redundant Access or as a way to establish an interactive remote desktop session with the target system. They may also be used as a component of malware to establish a reverse connection or back-connect to a service or adversary controlled system.

An adversary may use legitimate desktop support and remote access software, such as Team Viewer, Go2Assist, LogMein, AmmyyAdmin, etc, to establish an interactive command and control channel to target systems within networks. These services are commonly used as legitimate technical support software, and may be whitelisted within a target environment. Remote access tools like VNC, Ammy, and Teamviewer are used frequently when compared with other legitimate software commonly used by adversaries. (Citation: Symantec Living off the Land)

Detection: Monitoring when the user’s <code>.bash_history</code> is read can help alert to suspicious activity. While users do typically rely on their history of commands, they often access this history through other utilities like "history" instead of commands like <code>cat ~/.bash_history</code>.

Bash keeps track of the commands users type on the command-line with the "history" utility. Once a user logs out, the history is flushed to the user’s <code>.bash_history</code> file. For each user, this file resides at the same location: <code>~/.bash_history</code>. Typically, this file keeps track of the user’s last 500 commands. Users often type usernames and passwords on the command-line as parameters to programs, which then get saved to this file when they log out. Attackers can abuse this by looking through the file for potential credentials. (Citation: External to DA, the OS X Way)

Normal, benign system and network events that look like process discovery may be uncommon, depending on the environment and how they are used. Monitor processes and command-line arguments for actions that could be taken to gather system and network information. Remote access tools with built-in features may interact directly with the Windows API to gather information. Information may also be acquired through Windows system management tools such as Windows Management Instrumentation and PowerShell.

Detection: System and network discovery techniques normally occur throughout an operation as an adversary learns the environment. Data and events should not be viewed in isolation, but as part of a chain of behavior that could lead to other activities, such as Lateral Movement, based on the information obtained.

An example command that would obtain details on processes is "tasklist" using the Tasklist utility.

Adversaries may attempt to get information about running processes on a system. Information obtained could be used to gain an understanding of common software running on systems within the network.

Likewise, EFI modules can be collected and compared against a known-clean list of EFI executable binaries to detect potentially malicious modules. The CHIPSEC framework can be used for analysis to determine if firmware modifications have been performed. (Citation: McAfee CHIPSEC Blog) (Citation: Github CHIPSEC) (Citation: Intel HackingTeam UEFI Rootkit)

Detection: System firmware manipulation may be detected. (Citation: MITRE Trustworthy Firmware Measurement) Dump and inspect BIOS images on vulnerable systems and compare against known good images. (Citation: MITRE Copernicus) Analyze differences to determine if malicious changes have occurred. Log attempts to read/write to BIOS and compare against known patching behavior.

System firmware like BIOS and (U)EFI underly the functionality of a computer and may be modified by an adversary to perform or assist in malicious activity. Capabilities exist to overwrite the system firmware, which may give sophisticated adversaries a means to install malicious firmware updates as a means of persistence on a system that may be difficult to detect.

The BIOS (Basic Input/Output System) and The Unified Extensible Firmware Interface (UEFI) or Extensible Firmware Interface (EFI) are examples of system firmware that operate as the software interface between the operating system and hardware of a computer. (Citation: Wikipedia BIOS) (Citation: Wikipedia UEFI) (Citation: About UEFI)

Changes to these locations typically happen under normal conditions when legitimate software is installed. To increase confidence of malicious activity, data and events should not be viewed in isolation, but as part of a chain of behavior that could lead to other activities, such as network connections made for Command and Control, learning details about the environment through Discovery, and Lateral Movement.

Detection: Monitor Registry for changes to run keys that do not correlate with known software, patch cycles, etc. Monitor the start folder for additions or changes. Tools such as Sysinternals Autoruns may also be used to detect system changes that could be attempts at persistence, including listing the run keys' Registry locations and startup folders. (Citation: TechNet Autoruns) Suspicious program execution as startup programs may show up as outlier processes that have not been seen before when compared against historical data.

Adversaries can use these configuration locations to execute malware, such as remote access tools, to maintain persistence through system reboots. Adversaries may also use Masquerading to make the Registry entries look as if they are associated with legitimate programs.

Adding an entry to the "run keys" in the Registry or startup folder will cause the program referenced to be executed when a user logs in. (Citation: Microsoft Run Key) The program will be executed under the context of the user and will have the account’s associated permissions level.

Detection: Changes to service Registry entries and command-line invocation of tools capable of modifying services that do not correlate with known software, patch cycles, etc., may be suspicious. If a service is used only to execute a binary or script and not to persist, then it will likely be changed back to its original form shortly after the service is restarted so the service is not left broken, as is the case with the common administrator tool PsExec.

Adversaries may execute a binary, command, or script via a method that interacts with Windows services, such as the Service Control Manager. This can be done by either creating a new service or modifying an existing service. This technique is the execution used in conjunction with New Service and Modify Existing Service during service persistence or privilege escalation.

Detection: Analyze network data for uncommon data flows (e.g., a client sending significantly more data than it receives from a server). Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious. Analyze packet contents to detect communications that do not follow the expected protocol behavior for the port that is being used. (Citation: University of Birmingham C2)

Adversaries may conduct C2 communications over a non-standard port to bypass proxies and firewalls that have been improperly configured.

Detection: Use process monitoring to detect and analyze the execution and arguments of CMSTP.exe. Compare recent invocations of CMSTP.exe with prior history of known good arguments and loaded files to determine anomalous and potentially adversarial activity.

CMSTP.exe can also be abused to Bypass User Account Control and execute arbitrary commands from a malicious INF through an auto-elevated COM interface. (Citation: MSitPros CMSTP Aug 2017) (Citation: GitHub Ultimate AppLocker Bypass List)

Adversaries may supply CMSTP.exe with INF files infected with malicious commands. (Citation: Twitter CMSTP Usage Jan 2018) Similar to Regsvr32 / ”Squiblydoo”, CMSTP.exe may be abused to load and execute DLLs (Citation: MSitPros CMSTP Aug 2017) and/or COM scriptlets (SCT) from remote servers. (Citation: Twitter CMSTP Jan 2018) (Citation: GitHub Ultimate AppLocker Bypass List) This execution may also bypass AppLocker and other whitelisting defenses since CMSTP.exe is a legitimate, signed Microsoft application.

The Microsoft Connection Manager Profile Installer (CMSTP.exe) is a command-line program used to install Connection Manager service profiles. (Citation: Microsoft Connection Manager Oct 2009) CMSTP.exe accepts an installation information file (INF) as a parameter and installs a service profile leveraged for remote access connections.

Analyze new Control Panel items as well as those present on disk for malicious content. Both executable and CPL formats are compliant Portable Executable (PE) images and can be examined using traditional tools and methods, pending anti-reverse-engineering techniques. (Citation: TrendMicro CPL Malware Jan 2014)

Inventory Control Panel items to locate unregistered and potentially malicious files present on systems: *Executable format registered Control Panel items will have a globally unique identifier (GUID) and registration Registry entries in <code>HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\ControlPanel\NameSpace</code> and <code>HKEY_CLASSES_ROOT\CLSID{GUID}</code>. These entries may contain information about the Control Panel item such as its display name, path to the local file, and the command executed when opened in the Control Panel. (Citation: Microsoft Implementing CPL) * CPL format registered Control Panel items stored in the System32 directory are automatically shown in the Control Panel. Other Control Panel items will have registration entries in the <code>Cpls</code> and <code>Extended Properties</code> Registry keys of <code>HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Control Panel</code>. These entries may include information such as a GUID, path to the local file, and a canonical name used to launch the file programmatically (<code> WinExec("c:\windows\system32\control.exe {Canonical_Name}", SW_NORMAL);</code>) or from a command line (<code>control.exe /name {Canonical_Name}</code>). (Citation: Microsoft Implementing CPL) *Some Control Panel items are extensible via Shell extensions registered in <code>HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Controls Folder{name}\Shellex\PropertySheetHandlers</code> where {name} is the predefined name of the system item. (Citation: Microsoft Implementing CPL)

Detection: Monitor and analyze activity related to items associated with CPL files, such as the Windows Control Panel process binary (control.exe) and the Control_RunDLL and ControlRunDLLAsUser API functions in shell32.dll. When executed from the command line or clicked, control.exe will execute the CPL file (ex: <code>control.exe file.cpl</code>) before Rundll32 is used to call the CPL’s API functions (ex: <code>rundll32.exe shell32.dll,Control_RunDLL file.cpl</code>). CPL files can be executed directly via the CPL API function with just the latter Rundll32 command, which may bypass detections and/or execution filters for control.exe. (Citation: TrendMicro CPL Malware Jan 2014)

Adversaries can use Control Panel items as execution payloads to execute arbitrary commands. Malicious Control Panel items can be delivered via Spearphishing Attachment campaigns (Citation: TrendMicro CPL Malware Jan 2014) (Citation: TrendMicro CPL Malware Dec 2013) or executed as part of multi-stage malware. (Citation: Palo Alto Reaver Nov 2017) Control Panel items, specifically CPL files, may also bypass application and/or file extension whitelisting.

For ease of use, Control Panel items typically include graphical menus available to users after being registered and loaded into the Control Panel. (Citation: Microsoft Implementing CPL)

Windows Control Panel items are utilities that allow users to view and adjust computer settings. Control Panel items are registered executable (.exe) or Control Panel (.cpl) files, the latter are actually renamed dynamic-link library (.dll) files that export a CPlApplet function. (Citation: Microsoft Implementing CPL) (Citation: TrendMicro CPL Malware Jan 2014) Control Panel items can be executed directly from the command line, programmatically via an application programming interface (API) call, or by simply double-clicking the file. (Citation: Microsoft Implementing CPL) (Citation: TrendMicro CPL Malware Jan 2014) (Citation: TrendMicro CPL Malware Dec 2013)

Monitor for spawning of processes associated with COM objects, especially those invoked by a user different than the one currently logged on.

Detection: Monitor for COM objects loading DLLs and other modules not typically associated with the application. (Citation: Enigma Outlook DCOM Lateral Movement Nov 2017)

Adversaries may use DCOM for lateral movement. Through DCOM, adversaries operating in the context of an appropriately privileged user can remotely obtain arbitrary and even direct shellcode execution through Office applications (Citation: Enigma Outlook DCOM Lateral Movement Nov 2017) as well as other Windows objects that contain insecure methods. (Citation: Enigma MMC20 COM Jan 2017) (Citation: Enigma DCOM Lateral Movement Jan 2017) DCOM can also execute macros in existing documents (Citation: Enigma Excel DCOM Sept 2017) and may also invoke Dynamic Data Exchange (DDE) execution directly through a COM created instance of a Microsoft Office application (Citation: Cyberreason DCOM DDE Lateral Movement Nov 2017), bypassing the need for a malicious document.

Permissions to interact with local and remote server COM objects are specified by access control lists (ACL) in the Registry. (Citation: Microsoft COM) ACL (Citation: Microsoft Process Wide Com Keys) (Citation: Microsoft System Wide Com Keys) By default, only Administrators may remotely activate and launch COM objects through DCOM.

Windows Distributed Component Object Model (DCOM) is transparent middleware that extends the functionality of Component Object Model (COM) (Citation: Microsoft COM) beyond a local computer using remote procedure call (RPC) technology. COM is a component of the Windows application programming interface (API) that enables interaction between software objects. Through COM, a client object can call methods of server objects, which are typically Dynamic Link Libraries (DLL) or executables (EXE).

Detection: Exploitation for defense evasion may happen shortly after the system has been compromised to prevent detection during later actions for for additional tools that may be brought in and used. Detecting software exploitation may be difficult depending on the tools available. Software exploits may not always succeed or may cause the exploited process to become unstable or crash. Also look for behavior on the system that might indicate successful compromise, such as abnormal behavior of processes. This could include suspicious files written to disk, evidence of Process Injection for attempts to hide execution or evidence of Discovery.

Adversaries may have prior knowledge through reconnaissance that security software exists within an environment or they may perform checks during or shortly after the system is compromised for Security Software Discovery. The security software will likely be targeted directly for exploitation. There are examples of antivirus software being targeted by persistent threat groups to avoid detection.

Exploitation of a software vulnerability occurs when an adversary takes advantage of a programming error in a program, service, or within the operating system software or kernel itself to execute adversary-controlled code. Vulnerabilities may exist in defensive security software that can be used to disable or circumvent them.

Detection: The <code>/Library/StartupItems</code> folder can be monitored for changes. Similarly, the programs that are actually executed from this mechanism should be checked against a whitelist. Monitor processes that are executed during the bootup process to check for unusual or unknown applications and behavior.

An adversary can create the appropriate folders/files in the StartupItems directory to register their own persistence mechanism (Citation: Methods of Mac Malware Persistence). Additionally, since StartupItems run during the bootup phase of macOS, they will run as root. If an adversary is able to modify an existing Startup Item, then they will be able to Privilege Escalate as well.

Per Apple’s documentation, startup items execute during the final phase of the boot process and contain shell scripts or other executable files along with configuration information used by the system to determine the execution order for all startup items (Citation: Startup Items). This is technically a deprecated version (superseded by Launch Daemons), and thus the appropriate folder, <code>/Library/StartupItems</code> isn’t guaranteed to exist on the system by default, but does appear to exist by default on macOS Sierra. A startup item is a directory whose executable and configuration property list (plist), <code>StartupParameters.plist</code>, reside in the top-level directory.

Detection: This is a difficult technique to detect because adversary traffic would be masked by normal user traffic. No new processes are created and no additional software touches disk. Authentication logs can be used to audit logins to specific web applications, but determining malicious logins versus benign logins may be difficult if activity matches typical user behavior. Monitor for process injection against browser applications

Browser pivoting requires the SeDebugPrivilege and a high-integrity process to execute. Browser traffic is pivoted from the adversary’s browser through the user’s browser by setting up an HTTP proxy which will redirect any HTTP and HTTPS traffic. This does not alter the user’s traffic in any way. The proxy connection is severed as soon as the browser is closed. Whichever browser process the proxy is injected into, the adversary assumes the security context of that process. Browsers typically create a new process for each tab that is opened and permissions and certificates are separated accordingly. With these permissions, an adversary could browse to any resource on an intranet that is accessible through the browser and which the browser has sufficient permissions, such as Sharepoint or webmail. Browser pivoting also eliminates the security provided by 2-factor authentication. (Citation: cobaltstrike manual)

A specific example is when an adversary injects software into a browser that allows an them to inherit cookies, HTTP sessions, and SSL client certificates of a user and use the browser as a way to pivot into an authenticated intranet. (Citation: Cobalt Strike Browser Pivot) (Citation: ICEBRG Chrome Extensions)

Adversaries can take advantage of security vulnerabilities and inherent functionality in browser software to change content, modify behavior, and intercept information as part of various man in the browser techniques. (Citation: Wikipedia Man in the Browser)

Detection: Detecting software exploitation may be difficult depending on the tools available. Software exploits may not always succeed or may cause the exploited process to become unstable or crash. Also look for behavior on the system that might indicate successful compromise, such as abnormal behavior of processes. Credential resources obtained through exploitation may be detectable in use if they are not normally used or seen.

Exploitation of a software vulnerability occurs when an adversary takes advantage of a programming error in a program, service, or within the operating system software or kernel itself to execute adversary-controlled code. Credentialing and authentication mechanisms may be targeted for exploitation by adversaries as a means to gain access to useful credentials or circumvent the process to gain access to systems. One example of this is MS14-068, which targets Kerberos and can be used to forge Kerberos tickets using domain user permissions. (Citation: Technet MS14-068) (Citation: ADSecurity Detecting Forged Tickets) Exploitation for credential access may also result in Privilege Escalation depending on the process targeted or credentials obtained.

Detection: Monitor processes for those that may be used to modify binary headers. Monitor file systems for changes to application binaries and invalid checksums/signatures. Changes to binaries that do not line up with application updates or patches are also extremely suspicious.

Mach-O binaries have a series of headers that are used to perform certain operations when a binary is loaded. The LC_LOAD_DYLIB header in a Mach-O binary tells macOS and OS X which dynamic libraries (dylibs) to load during execution time. These can be added ad-hoc to the compiled binary as long adjustments are made to the rest of the fields and dependencies (Citation: Writing Bad Malware for OSX). There are tools available to perform these changes. Any changes will invalidate digital signatures on binaries because the binary is being modified. Adversaries can remediate this issue by simply removing the LC_CODE_SIGNATURE command from the binary so that the signature isn’t checked at load time (Citation: Malware Persistence on OS X).

Adversaries may target lsass.exe drivers to obtain execution and/or persistence. By either replacing or adding illegitimate drivers (e.g., DLL Side-Loading or DLL Search Order Hijacking), an adversary can achieve arbitrary code execution triggered by continuous LSA operations.

The Windows security subsystem is a set of components that manage and enforce the security policy for a computer or domain. The Local Security Authority (LSA) is the main component responsible for local security policy and user authentication. The LSA includes multiple dynamic link libraries (DLLs) associated with various other security functions, all of which run in the context of the LSA Subsystem Service (LSASS) lsass.exe process. (Citation: Microsoft Security Subsystem)

Monitor processes and command-line arguments for actions that could be taken to collect and combine files. Remote access tools with built-in features may interact directly with the Windows API to gather and copy to a location. Data may also be acquired and staged through Windows system management tools such as Windows Management Instrumentation and PowerShell.

Detection: Processes that appear to be reading files from disparate locations and writing them to the same directory or file may be an indication of data being staged, especially if they are suspected of performing encryption or compression on the files.

Interactive command shells may be used, and common functionality within cmd and bash may be used to copy data into a staging location.

Collected data is staged in a central location or directory prior to Exfiltration. Data may be kept in separate files or combined into one file through techniques such as Data Compressed or Data Encrypted.

Anti-virus can potentially detect malicious documents and files that are downloaded on the user’s computer. Endpoint sensing or network sensing can potentially detect malicious events once the file is opened (such as a Microsoft Word document or PDF reaching out to the internet or spawning Powershell.exe) for techniques such as Exploitation for Client Execution and Scripting.

Detection: Because most common third-party services used for spearphishing via service leverage TLS encryption, SSL/TLS inspection is generally required to detect the initial communication/delivery. With SSL/TLS inspection intrusion detection signatures or other security gateway appliances may be able to detect malware.

A common example is to build rapport with a target via social media, then send content to a personal webmail service that the target uses on their work computer. This allows an adversary to bypass some email restrictions on the work account, and the target is more likely to open the file since it’s something they were expecting. If the payload doesn’t work as expected, the adversary can continue normal communications and troubleshoot with the target on how to get it working.

All forms of spearphishing are electronically delivered social engineering targeted at a specific individual, company, or industry. In this scenario, adversaries send messages through various social media services, personal webmail, and other non-enterprise controlled services. These services are more likely to have a less-strict security policy than an enterprise. As with most kinds of spearphishing, the goal is to generate rapport with the target or get the target’s interest in some way. Adversaries will create fake social media accounts and message employees for potential job opportunities. Doing so allows a plausible reason for asking about services, policies, and software that’s running in an environment. The adversary can then send malicious links or attachments through these services.

Spearphishing via service is a specific variant of spearphishing. It is different from other forms of spearphishing in that it employs the use of third party services rather than directly via enterprise email channels.

Monitor processes and command-line arguments for actions that could create services. Remote access tools with built-in features may interact directly with the Windows API to perform these functions outside of typical system utilities. Services may also be created through Windows system management tools such as Windows Management Instrumentation and PowerShell, so additional logging may need to be configured to gather the appropriate data.

Tools such as Sysinternals Autoruns may also be used to detect system changes that could be attempts at persistence. (Citation: TechNet Autoruns) Look for changes to services that do not correlate with known software, patch cycles, etc. Suspicious program execution through services may show up as outlier processes that have not been seen before when compared against historical data.

Detection: Monitor service creation through changes in the Registry and common utilities using command-line invocation. New, benign services may be created during installation of new software. Data and events should not be viewed in isolation, but as part of a chain of behavior that could lead to other activities, such as network connections made for Command and Control, learning details about the environment through Discovery, and Lateral Movement.

Adversaries may install a new service that can be configured to execute at startup by using utilities to interact with services or by directly modifying the Registry. The service name may be disguised by using a name from a related operating system or benign software with Masquerading. Services may be created with administrator privileges but are executed under SYSTEM privileges, so an adversary may also use a service to escalate privileges from administrator to SYSTEM. Adversaries may also directly start services through Service Execution.

When operating systems boot up, they can start programs or applications called services that perform background system functions. (Citation: TechNet Services) A service’s configuration information, including the file path to the service’s executable, is stored in the Windows Registry.

Detection: Network share connections may be common depending on how an network environment is used. Monitor command-line invocation of <code>net use</code> commands associated with establishing and removing remote shares over SMB, including following best practices for detection of Windows Admin Shares. SMB traffic between systems may also be captured and decoded to look for related network share session and file transfer activity. Windows authentication logs are also useful in determining when authenticated network shares are established and by which account, and can be used to correlate network share activity to other events to investigate potentially malicious activity.

Adversaries may remove share connections that are no longer useful in order to clean up traces of their operation.

Windows shared drive and Windows Admin Shares connections can be removed when no longer needed. Net is an example utility that can be used to remove network share connections with the <code>net use \\system\share /delete</code> command. (Citation: Technet Net Use)

Detection: Monitor access to files and directories related to cryptographic keys and certificates as a means for potentially detecting access patterns that may indicate collection and exfiltration activity. Collect authentication logs and look for potentially abnormal activity that may indicate improper use of keys or certificates for remote authentication.

Adversary tools have been discovered that search compromised systems for file extensions relating to cryptographic keys and certificates. (Citation: Kaspersky Careto) (Citation: Palo Alto Prince of Persia)

Private keys should require a password or passphrase for operation, so an adversary may also use Input Capture for keylogging or attempt to Brute Force the passphrase off-line.

Adversaries may gather private keys from compromised systems for use in authenticating to Remote Services like SSH or for use in decrypting other collected files such as email. Common key and certificate file extensions include: .key, .pgp, .gpg, .ppk., .p12, .pem, pfx, .cer, .p7b, .asc. Adversaries may also look in common key directories, such as <code>~/.ssh</code> for SSH keys on *nix-based systems or <code>C:\Users\(username)\.ssh\</code> on Windows.

Analyze process behavior to determine if a process is performing actions it usually does not, such as opening network connections, reading files, or other suspicious actions that could relate to post-compromise behavior.

Scan file objects reported during the PsSetCreateProcessNotifyRoutine, (Citation: Microsoft PsSetCreateProcessNotifyRoutine routine) which triggers a callback whenever a process is created or deleted, specifically looking for file objects with enabled write access. (Citation: BlackHat Process Doppelgänging Dec 2017) Also consider comparing file objects loaded in memory to the corresponding file on disk. (Citation: hasherezade Process Doppelgänging Dec 2017)

Detection: Monitor and analyze calls to CreateTranscation, CreateFileTransacted, RollbackTransaction, and other rarely used functions indicative of TxF activity. Process Doppelgänging also invokes an outdated and undocumented implementation of the Windows process loader via calls to NtCreateProcessEx and NtCreateThreadEx as well as API calls used to modify memory within another process, such as WriteProcessMemory. (Citation: BlackHat Process Doppelgänging Dec 2017) (Citation: hasherezade Process Doppelgänging Dec 2017)

Process Doppelgänging is implemented in 4 steps (Citation: BlackHat Process Doppelgänging Dec 2017): * Transact – Create a TxF transaction using a legitimate executable then overwrite the file with malicious code. These changes will be isolated and only visible within the context of the transaction. * Load – Create a shared section of memory and load the malicious executable. * Rollback – Undo changes to original executable, effectively removing malicious code from the file system. * Animate – Create a process from the tainted section of memory and initiate execution.

Adversaries may leverage TxF to a perform a file-less variation of Process Injection called Process Doppelgänging. Similar to Process Hollowing, Process Doppelgänging involves replacing the memory of a legitimate process, enabling the veiled execution of malicious code that may evade defenses and detection. Process Doppelgänging’s use of TxF also avoids the use of highly-monitored API functions such as NtUnmapViewOfSection, VirtualProtectEx, and SetThreadContext. (Citation: BlackHat Process Doppelgänging Dec 2017)

Windows Transactional NTFS (TxF) was introduced in Vista as a method to perform safe file operations. (Citation: Microsoft TxF) To ensure data integrity, TxF enables only one transacted handle to write to a file at a given time. Until the write handle transaction is terminated, all other handles are isolated from the writer and may only read the committed version of the file that existed at the time the handle was opened. (Citation: Microsoft Basic TxF Concepts) To avoid corruption, TxF performs an automatic rollback if the system or application fails during a write transaction. (Citation: Microsoft Where to use TxF)

Detection: Establish monitoring for activity conducted by second and third party providers and other trusted entities that may be leveraged as a means to gain access to the network. Depending on the type of relationship, an adversary may have access to significant amounts of information about the target before conducting an operation, especially if the trusted relationship is based on IT services. Adversaries may be able to act quickly towards an objective, so proper monitoring for behavior related to Credential Access, Lateral Movement, and Collection will be important to detect the intrusion.

Organizations often grant elevated access to second or third-party external providers in order to allow them to manage internal systems. Some examples of these relationships include IT services contractors, managed security providers, infrastructure contractors (e.g. HVAC, elevators, physical security). The third-party provider’s access may be intended to be limited to the infrastructure being maintained, but may exist on the same network as the rest of the enterprise. As such, Valid Accounts used by the other party for access to internal network systems may be compromised and used.

Adversaries may breach or otherwise leverage organizations who have access to intended victims. Access through trusted third party relationship exploits an existing connection that may not be protected or receives less scrutiny than standard mechanisms of gaining access to a network.

Monitor for Microsoft Office applications loading DLLs and other modules not typically associated with the application.

Detection: OLE and Office Open XML files can be scanned for ‘DDEAUTO', ‘DDE’, and other strings indicative of DDE execution. (Citation: NVisio Labs DDE Detection Oct 2017)

Adversaries may use DDE to execute arbitrary commands. Microsoft Office documents can be poisoned with DDE commands (Citation: SensePost PS DDE May 2016) (Citation: Kettle CSV DDE Aug 2014), directly or through embedded files (Citation: Enigma Reviving DDE Jan 2018), and used to deliver execution via phishing campaigns or hosted Web content, avoiding the use of Visual Basic for Applications (VBA) macros. (Citation: SensePost MacroLess DDE Oct 2017) DDE could also be leveraged by an adversary operating on a compromised machine who does not have direct access to command line execution.

Object Linking and Embedding (OLE), or the ability to link data between documents, was originally implemented through DDE. Despite being superseded by COM, DDE may be enabled in Windows 10 and most of Microsoft Office 2016 via Registry keys. (Citation: BleepingComputer DDE Disabled in Word Dec 2017) (Citation: Microsoft ADV170021 Dec 2017) (Citation: Microsoft DDE Advisory Nov 2017)

Windows Dynamic Data Exchange (DDE) is a client-server protocol for one-time and/or continuous inter-process communication (IPC) between applications. Once a link is established, applications can autonomously exchange transactions consisting of strings, warm data links (notifications when a data item changes), hot data links (duplications of changes to a data item), and requests for command execution.

Detection: This technique is abusing normal functionality in macOS and Linux systems, but sudo has the ability to log all input and output based on the <code>LOG_INPUT</code> and <code>LOG_OUTPUT</code> directives in the <code>/etc/sudoers</code> file.

The OSX Proton Malware has disabled <code>tty_tickets</code> to potentially make scripting easier by issuing <code>echo \'Defaults !tty_tickets\' >> /etc/sudoers</code> (Citation: cybereason osx proton). In order for this change to be reflected, the Proton malware also must issue <code>killall Terminal</code>. As of macOS Sierra, the sudoers file has <code>tty_tickets</code> enabled by default.

Adversaries can abuse poor configurations of this to escalate privileges without needing the user’s password. <code>/var/db/sudo</code>'s timestamp can be monitored to see if it falls within the <code>timestamp_timeout</code> range. If it does, then malware can execute sudo commands without needing to supply the user’s password. Combined with <code>tty_tickets</code> being disabled, means adversaries can do this from any tty for that user.

The <code>sudo</code> command "allows a system administrator to delegate authority to give certain users (or groups of users) the ability to run some (or all) commands as root or another user while providing an audit trail of the commands and their arguments" (Citation: sudo man page 2018). Since sudo was made for the system administrator, it has some useful configuration features such as a <code>timestamp_timeout</code> that is the amount of time in minutes between instances of <code>sudo</code> before it will re-prompt for a password. This is because <code>sudo</code> has the ability to cache credentials for a period of time. Sudo creates (or touches) a file at <code>/var/db/sudo</code> with a timestamp of when sudo was last run to determine this timeout. Additionally, there is a <code>tty_tickets</code> variable that treats each new tty (terminal session) in isolation. This means that, for example, the sudo timeout of one tty will not affect another tty (you will have to type the password again).

Detection: The <code>/etc/rc.common</code> file can be monitored to detect changes from the company policy. Monitor process execution resulting from the rc.common script for unusual or unknown applications or behavior.

Adversaries can use the rc.common file as a way to hide code for persistence that will execute on each reboot as the root user (Citation: Methods of Mac Malware Persistence).

During the boot process, macOS executes <code>source /etc/rc.common</code>, which is a shell script containing various utility functions. This file also defines routines for processing command-line arguments and for gathering system settings, and is thus recommended to include in the start of Startup Item Scripts (Citation: Startup Items). In macOS and OS X, this is now a deprecated technique in favor of launch agents and launch daemons, but is currently still used.

Monitor processes and command-line arguments for actions that could be done before or after code injection has occurred and correlate the information with related event information. Code injection may also be performed using PowerShell with tools such as PowerSploit, (Citation: Powersploit) so additional PowerShell monitoring may be required to cover known implementations of this behavior.

Monitor for named pipe creation and connection events (Event IDs 17 and 18) for possible indicators of infected processes with external modules. (Citation: Microsoft Sysmon v6 May 2017)

Monitoring for Linux specific calls such as the ptrace system call, the use of LD_PRELOAD environment variable, or dlfcn dynamic linking API calls, should not generate large amounts of data due to their specialized nature, and can be a very effective method to detect some of the common process injection methods. (Citation: ArtOfMemoryForensics) (Citation: GNU Acct) (Citation: RHEL auditd) (Citation: Chokepoint preload rootkits)

Detection: Monitoring Windows API calls indicative of the various types of code injection may generate a significant amount of data and may not be directly useful for defense unless collected under specific circumstances for known bad sequences of calls, since benign use of API functions may be common and difficult to distinguish from malicious behavior. API calls such as CreateRemoteThread, SuspendThread/SetThreadContext/ResumeThread, QueueUserAPC, and those that can be used to modify memory within another process, such as WriteProcessMemory, may be used for this technique. (Citation: Engame Process Injection July 2017)

Malware commonly utilizes process injection to access system resources through which Persistence and other environment modifications can be made. More sophisticated samples may perform multiple process injections to segment modules and further evade detection, utilizing named pipes or other inter-process communication (IPC) mechanisms as a communication channel.

Implementations for Linux and OS X/macOS systems include: (Citation: Datawire Code Injection) (Citation: Uninformed Needle) *'''LD_PRELOAD, LD_LIBRARY_PATH''' (Linux), '''DYLD_INSERT_LIBRARIES''' (Mac OS X) environment variables, or the dlfcn application programming interface (API) can be used to dynamically load a library (shared object) in a process which can be used to intercept API calls from the running process. (Citation: Phrack halfdead 1997) *'''Ptrace system calls''' can be used to attach to a running process and modify it in runtime. (Citation: Uninformed Needle) *'''/proc/[pid]/mem''' provides access to the memory of the process and can be used to read/write arbitrary data to it. This technique is very rare due to its complexity. (Citation: Uninformed Needle) *'''VDSO hijacking''' performs runtime injection on ELF binaries by manipulating code stubs mapped in from the linux-vdso.so shared object. (Citation: VDSO hijack 2009)

There are multiple approaches to injecting code into a live process. Windows implementations include: (Citation: Engame Process Injection July 2017) * '''Dynamic-link library (DLL) injection''' involves writing the path to a malicious DLL inside a process then invoking execution by creating a remote thread. * '''Portable executable injection''' involves writing malicious code directly into the process (without a file on disk) then invoking execution with either additional code or by creating a remote thread. The displacement of the injected code introduces the additional requirement for functionality to remap memory references. Variations of this method such as reflective DLL injection (writing a self-mapping DLL into a process) and memory module (map DLL when writing into process) overcome the address relocation issue. (Citation: Endgame HuntingNMemory June 2017) * '''Thread execution hijacking''' involves injecting malicious code or the path to a DLL into a thread of a process. Similar to Process Hollowing, the thread must first be suspended. * '''Asynchronous Procedure Call''' (APC) injection involves attaching malicious code to the APC Queue (Citation: Microsoft APC) of a process’s thread. Queued APC functions are executed when the thread enters an alterable state. AtomBombing (Citation: ENSIL AtomBombing Oct 2016) is a variation that utilizes APCs to invoke malicious code previously written to the global atom table. (Citation: Microsoft Atom Table) * '''Thread Local Storage''' (TLS) callback injection involves manipulating pointers inside a portable executable (PE) to redirect a process to malicious code before reaching the code’s legitimate entry point. (Citation: FireEye TLS Nov 2017)

Process injection is a method of executing arbitrary code in the address space of a separate live process. Running code in the context of another process may allow access to the process’s memory, system/network resources, and possibly elevated privileges. Execution via process injection may also evade detection from security products since the execution is masked under a legitimate process.

Detection: Monitor the Registry for changes to the LSA Registry keys. Monitor the LSA process for DLL loads. Windows 8.1 and Windows Server 2012 R2 may generate events when unsigned DLLs try to load into the LSA by setting the Registry key <code>HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Image File Execution Options\LSASS.exe</code> with AuditLevel = 8. (Citation: Graeber 2014) (Citation: Microsoft Configure LSA)

Adversaries can use the autostart mechanism provided by LSA Authentication Packages for persistence by placing a reference to a binary in the Windows Registry location <code>HKLM\SYSTEM\CurrentControlSet\Control\Lsa\</code> with the key value of <code>"Authentication Packages"=<target binary></code>. The binary will then be executed by the system when the authentication packages are loaded.

Windows Authentication Package DLLs are loaded by the Local Security Authority (LSA) process at system start. They provide support for multiple logon processes and multiple security protocols to the operating system. (Citation: MSDN Authentication Packages)

In general, analyze network data for uncommon data flows (e.g., a client sending significantly more data than it receives from a server). Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious. Analyze packet contents to detect communications that do not follow the expected protocol behavior for the port that is being used. (Citation: University of Birmingham C2)

With Custom Cryptographic Protocol, if malware uses encryption with symmetric keys, it may be possible to obtain the algorithm and key from samples and use them to decode network traffic to detect malware communications signatures. (Citation: Fidelis DarkComet)

Detection: If malware uses Standard Cryptographic Protocol, SSL/TLS inspection can be used to detect command and control traffic within some encrypted communication channels. (Citation: SANS Decrypting SSL) SSL/TLS inspection does come with certain risks that should be considered before implementing to avoid potential security issues such as incomplete certificate validation. (Citation: SEI SSL Inspection Risks) After SSL/TLS inspection, additional cryptographic analysis may be needed to analyze the second layer of encryption.

An adversary performs C2 communications using multiple layers of encryption, typically (but not exclusively) tunneling a custom encryption scheme within a protocol encryption scheme such as HTTPS or SMTPS.

Some adversaries may employ sophisticated means to compromise computer components and install malicious firmware that will execute adversary code outside of the operating system and main system firmware or BIOS. This technique may be similar to System Firmware but conducted upon other system components that may not have the same capability or level of integrity checking. Malicious device firmware could provide both a persistent level of access to systems despite potential typical failures to maintain access and hard disk re-images, as well as a way to evade host software-based defenses and integrity checks.

Normal, benign system and network events related to legitimate remote system discovery may be uncommon, depending on the environment and how they are used. Monitor processes and command-line arguments for actions that could be taken to gather system and network information. Remote access tools with built-in features may interact directly with the Windows API to gather information. Information may also be acquired through Windows system management tools such as Windows Management Instrumentation and PowerShell.

Detection: System and network discovery techniques normally occur throughout an operation as an adversary learns the environment. Data and events should not be viewed in isolation, but as part of a chain of behavior that could lead to other activities, such as Lateral Movement, based on the information obtained.

Adversaries may look for folders and drives shared on remote systems as a means of identifying sources of information to gather as a precursor for Collection and to identify potential systems of interest for Lateral Movement.

Net can be used to query a remote system for available shared drives using the <code>net view \\remotesystem</code> command. It can also be used to query shared drives on the local system using <code>net share</code>.

Networks often contain shared network drives and folders that enable users to access file directories on various systems across a network.

Detection: Monitor WMI event subscription entries, comparing current WMI event subscriptions to known good subscriptions for each host. Tools such as Sysinternals Autoruns may also be used to detect WMI changes that could be attempts at persistence. (Citation: TechNet Autoruns)

Windows Management Instrumentation (WMI) can be used to install event filters, providers, consumers, and bindings that execute code when a defined event occurs. Adversaries may use the capabilities of WMI to subscribe to an event and execute arbitrary code when that event occurs, providing persistence on a system. Adversaries may attempt to evade detection of this technique by compiling WMI scripts. (Citation: Dell WMI Persistence) Examples of events that may be subscribed to are the wall clock time or the computer’s uptime. (Citation: Kazanciyan 2014) Several threat groups have reportedly used this technique to maintain persistence. (Citation: Mandiant M-Trends 2015)

Detection: Monitor processes and command-line arguments to see if security tools are killed or stop running. Monitor Registry edits for modifications to services and startup programs that correspond to security tools. Lack of log or event file reporting may be suspicious.

Adversaries may disable security tools to avoid possible detection of their tools and activities. This can take the form of killing security software or event logging processes, deleting Registry keys so that tools do not start at run time, or other methods to interfere with security scanning or event reporting.

Monitor processes and command-line arguments for actions that could be taken to gather system and network information. Remote access tools with built-in features may interact directly with the Windows API to gather information. Information may also be acquired through Windows system management tools such as Windows Management Instrumentation and PowerShell.

Detection: System and network discovery techniques normally occur throughout an operation as an adversary learns the environment. Data and events should not be viewed in isolation, but as part of a chain of behavior that could lead to other activities based on the information obtained.

Adversaries may attempt to gather information about attached peripheral devices and components connected to a computer system. The information may be used to enhance their awareness of the system and network environment or may be used for further actions.

If the communications channel is unencrypted, compressed files can be detected in transit during exfiltration with a network intrusion detection or data loss prevention system analyzing file headers. (Citation: Wikipedia File Header Signatures)

Detection: Compression software and compressed files can be detected in many ways. Common utilities that may be present on the system or brought in by an adversary may be detectable through process monitoring and monitoring for command-line arguments for known compression utilities. This may yield a significant amount of benign events, depending on how systems in the environment are typically used.

An adversary may compress data (e.g., sensitive documents) that is collected prior to exfiltration in order to make it portable and minimize the amount of data sent over the network. The compression is done separately from the exfiltration channel and is performed using a custom program or algorithm, or a more common compression library or utility such as 7zip, RAR, ZIP, or zlib.

Monitor processes and command-line arguments for actions that could be taken to gather system and network information. Remote access tools with built-in features may interact directly with the Windows API to gather information. Information may also be acquired through Windows system management tools such as Windows Management Instrumentation and PowerShell.

Detection: System and network discovery techniques normally occur throughout an operation as an adversary learns the environment. Data and events should not be viewed in isolation, but as part of a chain of behavior that could lead to other acti