Class: Trojan
A malicious program designed to electronically spy on the user’s activities (intercept keyboard input, take screenshots, capture a list of active applications, etc.). The collected information is sent to the cybercriminal by various means, including email, FTP, and HTTP (by sending data in a request).Read more
Platform: Win32
Win32 is an API on Windows NT-based operating systems (Windows XP, Windows 7, etc.) that supports execution of 32-bit applications. One of the most widespread programming platforms in the world.Family: Pdfer
No family descriptionExamples
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Tactics and Techniques: Mitre*
Adversaries may send spearphishing emails with a malicious link in an attempt to gain access to victim systems. Spearphishing with a link is a specific variant of spearphishing. It is different from other forms of spearphishing in that it employs the use of links to download malware contained in email, instead of attaching malicious files to the email itself, to avoid defenses that may inspect email attachments. Spearphishing may also involve social engineering techniques, such as posing as a trusted source.
All forms of spearphishing are electronically delivered social engineering targeted at a specific individual, company, or industry. In this case, the malicious emails contain links. Generally, the links will be accompanied by social engineering text and require the user to actively click or copy and paste a URL into a browser, leveraging User Execution. The visited website may compromise the web browser using an exploit, or the user will be prompted to download applications, documents, zip files, or even executables depending on the pretext for the email in the first place.
Adversaries may also include links that are intended to interact directly with an email reader, including embedded images intended to exploit the end system directly. Additionally, adversaries may use seemingly benign links that abuse special characters to mimic legitimate websites (known as an “IDN homograph attack”).(Citation: CISA IDN ST05-016) URLs may also be obfuscated by taking advantage of quirks in the URL schema, such as the acceptance of integer- or hexadecimal-based hostname formats and the automatic discarding of text before an “@” symbol: for example, `hxxp://google.com@1157586937`.(Citation: Mandiant URL Obfuscation 2023)
Adversaries may also utilize links to perform consent phishing, typically with OAuth 2.0 request URLs that when accepted by the user provide permissions/access for malicious applications, allowing adversaries to Steal Application Access Tokens.(Citation: Trend Micro Pawn Storm OAuth 2017) These stolen access tokens allow the adversary to perform various actions on behalf of the user via API calls. (Citation: Microsoft OAuth 2.0 Consent Phishing 2021)
Adversaries may send spearphishing emails with a malicious link in an attempt to gain access to victim systems. Spearphishing with a link is a specific variant of spearphishing. It is different from other forms of spearphishing in that it employs the use of links to download malware contained in email, instead of attaching malicious files to the email itself, to avoid defenses that may inspect email attachments. Spearphishing may also involve social engineering techniques, such as posing as a trusted source.
All forms of spearphishing are electronically delivered social engineering targeted at a specific individual, company, or industry. In this case, the malicious emails contain links. Generally, the links will be accompanied by social engineering text and require the user to actively click or copy and paste a URL into a browser, leveraging User Execution. The visited website may compromise the web browser using an exploit, or the user will be prompted to download applications, documents, zip files, or even executables depending on the pretext for the email in the first place.
Adversaries may also include links that are intended to interact directly with an email reader, including embedded images intended to exploit the end system directly. Additionally, adversaries may use seemingly benign links that abuse special characters to mimic legitimate websites (known as an “IDN homograph attack”).(Citation: CISA IDN ST05-016) URLs may also be obfuscated by taking advantage of quirks in the URL schema, such as the acceptance of integer- or hexadecimal-based hostname formats and the automatic discarding of text before an “@” symbol: for example, `hxxp://google.com@1157586937`.(Citation: Mandiant URL Obfuscation 2023)
Adversaries may also utilize links to perform consent phishing, typically with OAuth 2.0 request URLs that when accepted by the user provide permissions/access for malicious applications, allowing adversaries to Steal Application Access Tokens.(Citation: Trend Micro Pawn Storm OAuth 2017) These stolen access tokens allow the adversary to perform various actions on behalf of the user via API calls. (Citation: Microsoft OAuth 2.0 Consent Phishing 2021)
Adversaries may send spearphishing emails with a malicious link in an attempt to gain access to victim systems. Spearphishing with a link is a specific variant of spearphishing. It is different from other forms of spearphishing in that it employs the use of links to download malware contained in email, instead of attaching malicious files to the email itself, to avoid defenses that may inspect email attachments. Spearphishing may also involve social engineering techniques, such as posing as a trusted source.
All forms of spearphishing are electronically delivered social engineering targeted at a specific individual, company, or industry. In this case, the malicious emails contain links. Generally, the links will be accompanied by social engineering text and require the user to actively click or copy and paste a URL into a browser, leveraging User Execution. The visited website may compromise the web browser using an exploit, or the user will be prompted to download applications, documents, zip files, or even executables depending on the pretext for the email in the first place.
Adversaries may also include links that are intended to interact directly with an email reader, including embedded images intended to exploit the end system directly. Additionally, adversaries may use seemingly benign links that abuse special characters to mimic legitimate websites (known as an “IDN homograph attack”).(Citation: CISA IDN ST05-016) URLs may also be obfuscated by taking advantage of quirks in the URL schema, such as the acceptance of integer- or hexadecimal-based hostname formats and the automatic discarding of text before an “@” symbol: for example, `hxxp://google.com@1157586937`.(Citation: Mandiant URL Obfuscation 2023)
Adversaries may also utilize links to perform consent phishing, typically with OAuth 2.0 request URLs that when accepted by the user provide permissions/access for malicious applications, allowing adversaries to Steal Application Access Tokens.(Citation: Trend Micro Pawn Storm OAuth 2017) These stolen access tokens allow the adversary to perform various actions on behalf of the user via API calls. (Citation: Microsoft OAuth 2.0 Consent Phishing 2021)
An adversary may rely upon a user clicking a malicious link in order to gain execution. Users may be subjected to social engineering to get them to click on a link that will lead to code execution. This user action will typically be observed as follow-on behavior from Spearphishing Link. Clicking on a link may also lead to other execution techniques such as exploitation of a browser or application vulnerability via Exploitation for Client Execution. Links may also lead users to download files that require execution via Malicious File.
An adversary may rely upon a user clicking a malicious link in order to gain execution. Users may be subjected to social engineering to get them to click on a link that will lead to code execution. This user action will typically be observed as follow-on behavior from Spearphishing Link. Clicking on a link may also lead to other execution techniques such as exploitation of a browser or application vulnerability via Exploitation for Client Execution. Links may also lead users to download files that require execution via Malicious File.
Adversaries may achieve persistence by adding a program to a startup folder or referencing it with a Registry run key. 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) These programs will be executed under the context of the user and will have the account’s associated permissions level.
The following run keys are created by default on Windows systems:
* HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRun
* HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRunOnce
* HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
* HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunOnce
Run keys may exist under multiple hives.(Citation: Microsoft Wow6432Node 2018)(Citation: Malwarebytes Wow6432Node 2016) The HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunOnceEx is also available but is not created by default on Windows Vista and newer. Registry run key entries can reference programs directly or list them as a dependency.(Citation: Microsoft Run Key) For example, it is possible to load a DLL at logon using a “Depend” key with RunOnceEx: reg add HKLMSOFTWAREMicrosoftWindowsCurrentVersionRunOnceEx 001Depend /v 1 /d "C:tempevil[.]dll" (Citation: Oddvar Moe RunOnceEx Mar 2018)
Placing a program within a startup folder will also cause that program to execute when a user logs in. There is a startup folder location for individual user accounts as well as a system-wide startup folder that will be checked regardless of which user account logs in. The startup folder path for the current user is C:Users\[Username]AppDataRoamingMicrosoftWindowsStart MenuProgramsStartup. The startup folder path for all users is C:ProgramDataMicrosoftWindowsStart MenuProgramsStartUp.
The following Registry keys can be used to set startup folder items for persistence:
* HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionExplorerUser Shell Folders
* HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionExplorerShell Folders
* HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionExplorerShell Folders
* HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionExplorerUser Shell Folders
The following Registry keys can control automatic startup of services during boot:
* HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunServicesOnce
* HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRunServicesOnce
* HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunServices
* HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRunServices
Using policy settings to specify startup programs creates corresponding values in either of two Registry keys:
* HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionPoliciesExplorerRun
* HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionPoliciesExplorerRun
Programs listed in the load value of the registry key HKEY_CURRENT_USERSoftwareMicrosoftWindows NTCurrentVersionWindows run automatically for the currently logged-on user.
By default, the multistring BootExecute value of the registry key HKEY_LOCAL_MACHINESystemCurrentControlSetControlSession Manager is set to autocheck autochk *. This value causes Windows, at startup, to check the file-system integrity of the hard disks if the system has been shut down abnormally. Adversaries can add other programs or processes to this registry value which will automatically launch at boot.
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.
Adversaries may achieve persistence by adding a program to a startup folder or referencing it with a Registry run key. 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) These programs will be executed under the context of the user and will have the account’s associated permissions level.
The following run keys are created by default on Windows systems:
* HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRun
* HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRunOnce
* HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
* HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunOnce
Run keys may exist under multiple hives.(Citation: Microsoft Wow6432Node 2018)(Citation: Malwarebytes Wow6432Node 2016) The HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunOnceEx is also available but is not created by default on Windows Vista and newer. Registry run key entries can reference programs directly or list them as a dependency.(Citation: Microsoft Run Key) For example, it is possible to load a DLL at logon using a “Depend” key with RunOnceEx: reg add HKLMSOFTWAREMicrosoftWindowsCurrentVersionRunOnceEx 001Depend /v 1 /d "C:tempevil[.]dll" (Citation: Oddvar Moe RunOnceEx Mar 2018)
Placing a program within a startup folder will also cause that program to execute when a user logs in. There is a startup folder location for individual user accounts as well as a system-wide startup folder that will be checked regardless of which user account logs in. The startup folder path for the current user is C:Users\[Username]AppDataRoamingMicrosoftWindowsStart MenuProgramsStartup. The startup folder path for all users is C:ProgramDataMicrosoftWindowsStart MenuProgramsStartUp.
The following Registry keys can be used to set startup folder items for persistence:
* HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionExplorerUser Shell Folders
* HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionExplorerShell Folders
* HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionExplorerShell Folders
* HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionExplorerUser Shell Folders
The following Registry keys can control automatic startup of services during boot:
* HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunServicesOnce
* HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRunServicesOnce
* HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunServices
* HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRunServices
Using policy settings to specify startup programs creates corresponding values in either of two Registry keys:
* HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionPoliciesExplorerRun
* HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionPoliciesExplorerRun
Programs listed in the load value of the registry key HKEY_CURRENT_USERSoftwareMicrosoftWindows NTCurrentVersionWindows run automatically for the currently logged-on user.
By default, the multistring BootExecute value of the registry key HKEY_LOCAL_MACHINESystemCurrentControlSetControlSession Manager is set to autocheck autochk *. This value causes Windows, at startup, to check the file-system integrity of the hard disks if the system has been shut down abnormally. Adversaries can add other programs or processes to this registry value which will automatically launch at boot.
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.
Adversaries may duplicate then impersonate another user’s existing token to escalate privileges and bypass access controls. For example, an adversary can duplicate an existing token using `DuplicateToken` or `DuplicateTokenEx`. The token can then be used with `ImpersonateLoggedOnUser` to allow the calling thread to impersonate a logged on user’s security context, or with `SetThreadToken` to assign the impersonated token to a thread.
An adversary may perform Token Impersonation/Theft when they have a specific, existing process they want to assign the duplicated token to. For example, this may be useful for when the target user has a non-network logon session on the system.
When an adversary would instead use a duplicated token to create a new process rather than attaching to an existing process, they can additionally Create Process with Token using `CreateProcessWithTokenW` or `CreateProcessAsUserW`. Token Impersonation/Theft is also distinct from Make and Impersonate Token in that it refers to duplicating an existing token, rather than creating a new one.
Adversaries may duplicate then impersonate another user’s existing token to escalate privileges and bypass access controls. For example, an adversary can duplicate an existing token using `DuplicateToken` or `DuplicateTokenEx`. The token can then be used with `ImpersonateLoggedOnUser` to allow the calling thread to impersonate a logged on user’s security context, or with `SetThreadToken` to assign the impersonated token to a thread.
An adversary may perform Token Impersonation/Theft when they have a specific, existing process they want to assign the duplicated token to. For example, this may be useful for when the target user has a non-network logon session on the system.
When an adversary would instead use a duplicated token to create a new process rather than attaching to an existing process, they can additionally Create Process with Token using `CreateProcessWithTokenW` or `CreateProcessAsUserW`. Token Impersonation/Theft is also distinct from Make and Impersonate Token in that it refers to duplicating an existing token, rather than creating a new one.
Adversaries may achieve persistence by adding a program to a startup folder or referencing it with a Registry run key. 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) These programs will be executed under the context of the user and will have the account’s associated permissions level.
The following run keys are created by default on Windows systems:
* HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRun
* HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRunOnce
* HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
* HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunOnce
Run keys may exist under multiple hives.(Citation: Microsoft Wow6432Node 2018)(Citation: Malwarebytes Wow6432Node 2016) The HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunOnceEx is also available but is not created by default on Windows Vista and newer. Registry run key entries can reference programs directly or list them as a dependency.(Citation: Microsoft Run Key) For example, it is possible to load a DLL at logon using a “Depend” key with RunOnceEx: reg add HKLMSOFTWAREMicrosoftWindowsCurrentVersionRunOnceEx 001Depend /v 1 /d "C:tempevil[.]dll" (Citation: Oddvar Moe RunOnceEx Mar 2018)
Placing a program within a startup folder will also cause that program to execute when a user logs in. There is a startup folder location for individual user accounts as well as a system-wide startup folder that will be checked regardless of which user account logs in. The startup folder path for the current user is C:Users\[Username]AppDataRoamingMicrosoftWindowsStart MenuProgramsStartup. The startup folder path for all users is C:ProgramDataMicrosoftWindowsStart MenuProgramsStartUp.
The following Registry keys can be used to set startup folder items for persistence:
* HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionExplorerUser Shell Folders
* HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionExplorerShell Folders
* HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionExplorerShell Folders
* HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionExplorerUser Shell Folders
The following Registry keys can control automatic startup of services during boot:
* HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunServicesOnce
* HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRunServicesOnce
* HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunServices
* HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRunServices
Using policy settings to specify startup programs creates corresponding values in either of two Registry keys:
* HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionPoliciesExplorerRun
* HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionPoliciesExplorerRun
Programs listed in the load value of the registry key HKEY_CURRENT_USERSoftwareMicrosoftWindows NTCurrentVersionWindows run automatically for the currently logged-on user.
By default, the multistring BootExecute value of the registry key HKEY_LOCAL_MACHINESystemCurrentControlSetControlSession Manager is set to autocheck autochk *. This value causes Windows, at startup, to check the file-system integrity of the hard disks if the system has been shut down abnormally. Adversaries can add other programs or processes to this registry value which will automatically launch at boot.
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.
Adversaries may modify file time attributes to hide new or changes to existing files. Timestomping is a technique that modifies the timestamps of a file (the modify, access, create, and change times), often to mimic files that are in the same folder. This is done, for example, on files that have been modified or created by the adversary so that they do not appear conspicuous to forensic investigators or file analysis tools.
Timestomping may be used along with file name Masquerading to hide malware and tools.(Citation: WindowsIR Anti-Forensic Techniques)
Adversaries may modify file time attributes to hide new or changes to existing files. Timestomping is a technique that modifies the timestamps of a file (the modify, access, create, and change times), often to mimic files that are in the same folder. This is done, for example, on files that have been modified or created by the adversary so that they do not appear conspicuous to forensic investigators or file analysis tools.
Timestomping may be used along with file name Masquerading to hide malware and tools.(Citation: WindowsIR Anti-Forensic Techniques)
Adversaries may interact with the Windows Registry to hide configuration information within Registry keys, remove information as part of cleaning up, or as part of other techniques to aid in persistence and execution.
Access to specific areas of the Registry depends on account permissions, some requiring administrator-level access. The built-in Windows command-line utility Reg may be used for local or remote Registry modification. (Citation: Microsoft Reg) Other tools may also be used, such as a remote access tool, which may contain functionality to interact with the Registry through the Windows API.
Registry modifications may also include actions to hide keys, such as prepending key names with a null character, which will cause an error and/or be ignored when read via Reg or other utilities using the Win32 API. (Citation: Microsoft Reghide NOV 2006) Adversaries may abuse these pseudo-hidden keys to conceal payloads/commands used to maintain persistence. (Citation: TrendMicro POWELIKS AUG 2014) (Citation: SpectorOps Hiding Reg Jul 2017)
The Registry of a remote system may be modified to aid in execution of files as part of lateral movement. It requires the remote Registry service to be running on the target system. (Citation: Microsoft Remote) Often Valid Accounts are required, along with access to the remote system’s SMB/Windows Admin Shares for RPC communication.
Adversaries may duplicate then impersonate another user’s existing token to escalate privileges and bypass access controls. For example, an adversary can duplicate an existing token using `DuplicateToken` or `DuplicateTokenEx`. The token can then be used with `ImpersonateLoggedOnUser` to allow the calling thread to impersonate a logged on user’s security context, or with `SetThreadToken` to assign the impersonated token to a thread.
An adversary may perform Token Impersonation/Theft when they have a specific, existing process they want to assign the duplicated token to. For example, this may be useful for when the target user has a non-network logon session on the system.
When an adversary would instead use a duplicated token to create a new process rather than attaching to an existing process, they can additionally Create Process with Token using `CreateProcessWithTokenW` or `CreateProcessAsUserW`. Token Impersonation/Theft is also distinct from Make and Impersonate Token in that it refers to duplicating an existing token, rather than creating a new one.
Adversaries may employ various system checks to detect and avoid virtualization and analysis environments. This may include changing behaviors based on the results of checks for the presence of artifacts indicative of a virtual machine environment (VME) or sandbox. If the adversary detects a VME, they may alter their malware to disengage from the victim or conceal the core functions of the implant. They may also search for VME artifacts before dropping secondary or additional payloads. Adversaries may use the information learned from Virtualization/Sandbox Evasion during automated discovery to shape follow-on behaviors.(Citation: Deloitte Environment Awareness)
Specific checks will vary based on the target and/or adversary, but may involve behaviors such as Windows Management Instrumentation, PowerShell, System Information Discovery, and Query Registry to obtain system information and search for VME artifacts. Adversaries may search for VME artifacts in memory, processes, file system, hardware, and/or the Registry. Adversaries may use scripting to automate these checks into one script and then have the program exit if it determines the system to be a virtual environment.
Checks could include generic system properties such as host/domain name and samples of network traffic. Adversaries may also check the network adapters addresses, CPU core count, and available memory/drive size.
Other common checks may enumerate services running that are unique to these applications, installed programs on the system, manufacturer/product fields for strings relating to virtual machine applications, and VME-specific hardware/processor instructions.(Citation: McAfee Virtual Jan 2017) In applications like VMWare, adversaries can also use a special I/O port to send commands and receive output.
Hardware checks, such as the presence of the fan, temperature, and audio devices, could also be used to gather evidence that can be indicative a virtual environment. Adversaries may also query for specific readings from these devices.(Citation: Unit 42 OilRig Sept 2018)
Adversaries may enumerate files and directories or may search in specific locations of a host or network share for certain information within a file system. Adversaries may use the information from File and Directory Discovery during automated discovery to shape follow-on behaviors, including whether or not the adversary fully infects the target and/or attempts specific actions.
Many command shell utilities can be used to obtain this information. Examples include dir, tree, ls, find, and locate.(Citation: Windows Commands JPCERT) Custom tools may also be used to gather file and directory information and interact with the Native API. Adversaries may also leverage a Network Device CLI on network devices to gather file and directory information (e.g. dir, show flash, and/or nvram).(Citation: US-CERT-TA18-106A)
Adversaries may enumerate files and directories or may search in specific locations of a host or network share for certain information within a file system. Adversaries may use the information from File and Directory Discovery during automated discovery to shape follow-on behaviors, including whether or not the adversary fully infects the target and/or attempts specific actions.
Many command shell utilities can be used to obtain this information. Examples include dir, tree, ls, find, and locate.(Citation: Windows Commands JPCERT) Custom tools may also be used to gather file and directory information and interact with the Native API. Adversaries may also leverage a Network Device CLI on network devices to gather file and directory information (e.g. dir, show flash, and/or nvram).(Citation: US-CERT-TA18-106A)
Adversaries may employ various system checks to detect and avoid virtualization and analysis environments. This may include changing behaviors based on the results of checks for the presence of artifacts indicative of a virtual machine environment (VME) or sandbox. If the adversary detects a VME, they may alter their malware to disengage from the victim or conceal the core functions of the implant. They may also search for VME artifacts before dropping secondary or additional payloads. Adversaries may use the information learned from Virtualization/Sandbox Evasion during automated discovery to shape follow-on behaviors.(Citation: Deloitte Environment Awareness)
Specific checks will vary based on the target and/or adversary, but may involve behaviors such as Windows Management Instrumentation, PowerShell, System Information Discovery, and Query Registry to obtain system information and search for VME artifacts. Adversaries may search for VME artifacts in memory, processes, file system, hardware, and/or the Registry. Adversaries may use scripting to automate these checks into one script and then have the program exit if it determines the system to be a virtual environment.
Checks could include generic system properties such as host/domain name and samples of network traffic. Adversaries may also check the network adapters addresses, CPU core count, and available memory/drive size.
Other common checks may enumerate services running that are unique to these applications, installed programs on the system, manufacturer/product fields for strings relating to virtual machine applications, and VME-specific hardware/processor instructions.(Citation: McAfee Virtual Jan 2017) In applications like VMWare, adversaries can also use a special I/O port to send commands and receive output.
Hardware checks, such as the presence of the fan, temperature, and audio devices, could also be used to gather evidence that can be indicative a virtual environment. Adversaries may also query for specific readings from these devices.(Citation: Unit 42 OilRig Sept 2018)
Adversaries may modify file time attributes to hide new or changes to existing files. Timestomping is a technique that modifies the timestamps of a file (the modify, access, create, and change times), often to mimic files that are in the same folder. This is done, for example, on files that have been modified or created by the adversary so that they do not appear conspicuous to forensic investigators or file analysis tools.
Timestomping may be used along with file name Masquerading to hide malware and tools.(Citation: WindowsIR Anti-Forensic Techniques)
Adversaries may modify file time attributes to hide new or changes to existing files. Timestomping is a technique that modifies the timestamps of a file (the modify, access, create, and change times), often to mimic files that are in the same folder. This is done, for example, on files that have been modified or created by the adversary so that they do not appear conspicuous to forensic investigators or file analysis tools.
Timestomping may be used along with file name Masquerading to hide malware and tools.(Citation: WindowsIR Anti-Forensic Techniques)
Adversaries may communicate using OSI application layer protocols to avoid detection/network filtering 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 may utilize many different protocols, including those used for web browsing, transferring files, electronic mail, or DNS. For connections that occur internally within an enclave (such as those between a proxy or pivot node and other nodes), commonly used protocols are SMB, SSH, or RDP.
Adversaries may transfer tools or other files from an external system into a compromised environment. Tools or files may be copied from an external adversary-controlled system to the victim network through the command and control channel or through alternate protocols such as ftp. Once present, adversaries may also transfer/spread tools between victim devices within a compromised environment (i.e. Lateral Tool Transfer).
On Windows, adversaries may use various utilities to download tools, such as `copy`, `finger`, certutil, and PowerShell commands such as IEX(New-Object Net.WebClient).downloadString() and Invoke-WebRequest. On Linux and macOS systems, a variety of utilities also exist, such as `curl`, `scp`, `sftp`, `tftp`, `rsync`, `finger`, and `wget`.(Citation: t1105_lolbas)
Adversaries may also abuse installers and package managers, such as `yum` or `winget`, to download tools to victim hosts.
Files can also be transferred using various Web Services as well as native or otherwise present tools on the victim system.(Citation: PTSecurity Cobalt Dec 2016) In some cases, adversaries may be able to leverage services that sync between a web-based and an on-premises client, such as Dropbox or OneDrive, to transfer files onto victim systems. For example, by compromising a cloud account and logging into the service’s web portal, an adversary may be able to trigger an automatic syncing process that transfers the file onto the victim’s machine.(Citation: Dropbox Malware Sync)
* © 2024 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation.