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42 changes: 42 additions & 0 deletions yml/OSBinaries/Mofcomp.yml
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---
Name: Mofcomp.exe
Description: Compiler that parses a file containing MOF statements and adds the classes and class instances defined in the file to the WMI repository. Threat actors can leverage this binary to install malicious MOF scripts
Author: Daniel Gott
Created: 2022-07-19
Commands:
- Command: mofcomp.exe C:\Windows\SERVIC~1\MSSQL$~1\AppData\Local\Temp\xitmf

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Why this path? Since it is not explained, I'm guessing this should be generalised to {PATH_ABSOLUTE:.mof}

Description: Abuse of mofcomp.exe to parse a file which contains MOF statements in order create new classes as part of the WMI repository
Usecase: Threat actors can use mofcomp.exe to decompile a BMOF binary and then register a malicious class in the WMI repository
Category: Execute
Privileges: User

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We should include

    Tags:
      - Execute: MOF

MitreID: T1047
OperatingSystem: Windows Vista, Windows 7, Windows 8, Windows 8.1, Windows 10, Windows 11, Windows Server 2008+
- Command: mofcomp.exe C:\Programdata\x.mof
Description: Abuse of mofcomp.exe to parse a file which contains MOF statements in order create new classes as part of the WMI repository
Usecase: Threat actors can use mofcomp.exe to register a malicious MOF file as a new class in the WMI repository
Category: Execute
Privileges: User
MitreID: T1047
OperatingSystem: Windows Vista, Windows 7, Windows 8, Windows 8.1, Windows 10, Windows 11, Windows Server 2008+

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This is redundant if we generalise the first example, and can be removed.

Full_Path:
- Path: C:\Windows\System32\wbem\mofcomp.exe
- Path: C:\Windows\SysWOW64\wbem\mofcomp.exe
Code_Sample:
- Code: N/A

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This can be deleted

Detection:
- IOC: strange parent processes spawning mofcomp.exe like cmd.exe or powershell.exe
- Sigma: https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_susp_mofcomp_execution.yml

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No longer exists - should be using commit hashes like the example below anyway

- Sigma: https://github.com/The-DFIR-Report/Sigma-Rules/blob/75260568a7ffe61b2458ca05f6f25914efb44337/win_mofcomp_execution.yml
Resources:
- Link: https://docs.microsoft.com/en-us/windows/win32/wmisdk/mofcomp
- Link: https://docs.microsoft.com/en-us/windows/win32/wmisdk/managed-object-format--mof-
- Link: https://thedfirreport.com/2022/07/11/select-xmrig-from-sqlserver/
- Link: https://in.security/2019/04/03/an-intro-into-abusing-and-identifying-wmi-event-subscriptions-for-persistence/
- Link: https://medium.com/threatpunter/detecting-removing-wmi-persistence-60ccbb7dff96
Acknowledgement:
- Person: Daniel Gott
Handle: '@gott_cyber'
- Person: The DFIR Report
Handle: '@TheDFIRReport'
- Person: Nasreddine Bencherchali
Handle: '@nas_bench'
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