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: Penguish
No family descriptionExamples
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3BC9289A13A5E9BA33BE966BD59E1EEF
Tactics and Techniques: Mitre*
An adversary may rely upon a user opening a malicious file in order to gain execution. Users may be subjected to social engineering to get them to open a file that will lead to code execution. This user action will typically be observed as follow-on behavior from Spearphishing Attachment. Adversaries may use several types of files that require a user to execute them, including .doc, .pdf, .xls, .rtf, .scr, .exe, .lnk, .pif, and .cpl.
Adversaries may employ various forms of Masquerading and Obfuscated Files or Information to increase the likelihood that a user will open and successfully execute a malicious file. These methods may include using a familiar naming convention and/or password protecting the file and supplying instructions to a user on how to open it.(Citation: Password Protected Word Docs)
While Malicious File 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. This activity may also be seen shortly after Internal Spearphishing.
An adversary may rely upon a user opening a malicious file in order to gain execution. Users may be subjected to social engineering to get them to open a file that will lead to code execution. This user action will typically be observed as follow-on behavior from Spearphishing Attachment. Adversaries may use several types of files that require a user to execute them, including .doc, .pdf, .xls, .rtf, .scr, .exe, .lnk, .pif, and .cpl.
Adversaries may employ various forms of Masquerading and Obfuscated Files or Information to increase the likelihood that a user will open and successfully execute a malicious file. These methods may include using a familiar naming convention and/or password protecting the file and supplying instructions to a user on how to open it.(Citation: Password Protected Word Docs)
While Malicious File 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. This activity may also be seen shortly after Internal Spearphishing.
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 inject malicious code into process via process doppelganging in order to evade process-based defenses as well as possibly elevate privileges. Process doppelganging is a method of executing arbitrary code in the address space of a separate live process.
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)
Although deprecated, the TxF application programming interface (API) is still enabled as of Windows 10. (Citation: BlackHat Process Doppelganging Dec 2017)
Adversaries may abuse TxF to a perform a file-less variation of Process Injection. Similar to Process Hollowing, process doppelganging involves replacing the memory of a legitimate process, enabling the veiled execution of malicious code that may evade defenses and detection. Process doppelganging’s use of TxF also avoids the use of highly-monitored API functions such as NtUnmapViewOfSection, VirtualProtectEx, and SetThreadContext. (Citation: BlackHat Process Doppelganging Dec 2017)
Process Doppelganging is implemented in 4 steps (Citation: BlackHat Process Doppelganging 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.
This behavior will likely not result in elevated privileges since the injected process was spawned from (and thus inherits the security context) of the injecting process. However, execution via process doppelganging may evade detection from security products since the execution is masked under a legitimate process.
Adversaries may inject malicious code into process via process doppelganging in order to evade process-based defenses as well as possibly elevate privileges. Process doppelganging is a method of executing arbitrary code in the address space of a separate live process.
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)
Although deprecated, the TxF application programming interface (API) is still enabled as of Windows 10. (Citation: BlackHat Process Doppelganging Dec 2017)
Adversaries may abuse TxF to a perform a file-less variation of Process Injection. Similar to Process Hollowing, process doppelganging involves replacing the memory of a legitimate process, enabling the veiled execution of malicious code that may evade defenses and detection. Process doppelganging’s use of TxF also avoids the use of highly-monitored API functions such as NtUnmapViewOfSection, VirtualProtectEx, and SetThreadContext. (Citation: BlackHat Process Doppelganging Dec 2017)
Process Doppelganging is implemented in 4 steps (Citation: BlackHat Process Doppelganging 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.
This behavior will likely not result in elevated privileges since the injected process was spawned from (and thus inherits the security context) of the injecting process. However, execution via process doppelganging may evade detection from security products since the execution is masked under a legitimate process.
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 inject malicious code into process via process doppelganging in order to evade process-based defenses as well as possibly elevate privileges. Process doppelganging is a method of executing arbitrary code in the address space of a separate live process.
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)
Although deprecated, the TxF application programming interface (API) is still enabled as of Windows 10. (Citation: BlackHat Process Doppelganging Dec 2017)
Adversaries may abuse TxF to a perform a file-less variation of Process Injection. Similar to Process Hollowing, process doppelganging involves replacing the memory of a legitimate process, enabling the veiled execution of malicious code that may evade defenses and detection. Process doppelganging’s use of TxF also avoids the use of highly-monitored API functions such as NtUnmapViewOfSection, VirtualProtectEx, and SetThreadContext. (Citation: BlackHat Process Doppelganging Dec 2017)
Process Doppelganging is implemented in 4 steps (Citation: BlackHat Process Doppelganging 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.
This behavior will likely not result in elevated privileges since the injected process was spawned from (and thus inherits the security context) of the injecting process. However, execution via process doppelganging may evade detection from security products since the execution is masked under a legitimate process.
Adversaries may inject malicious code into process via process doppelganging in order to evade process-based defenses as well as possibly elevate privileges. Process doppelganging is a method of executing arbitrary code in the address space of a separate live process.
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)
Although deprecated, the TxF application programming interface (API) is still enabled as of Windows 10. (Citation: BlackHat Process Doppelganging Dec 2017)
Adversaries may abuse TxF to a perform a file-less variation of Process Injection. Similar to Process Hollowing, process doppelganging involves replacing the memory of a legitimate process, enabling the veiled execution of malicious code that may evade defenses and detection. Process doppelganging’s use of TxF also avoids the use of highly-monitored API functions such as NtUnmapViewOfSection, VirtualProtectEx, and SetThreadContext. (Citation: BlackHat Process Doppelganging Dec 2017)
Process Doppelganging is implemented in 4 steps (Citation: BlackHat Process Doppelganging 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.
This behavior will likely not result in elevated privileges since the injected process was spawned from (and thus inherits the security context) of the injecting process. However, execution via process doppelganging may evade detection from security products since the execution is masked under a legitimate process.
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.
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