T1218.003
Signed Binary Proxy Execution: CMSTP
Description from ATT&CK
Adversaries may abuse CMSTP to proxy execution of malicious code. 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.
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) (Citation: Endurant CMSTP July 2018) This execution may also bypass AppLocker and other application control defenses since CMSTP.exe is a legitimate binary that may be signed by Microsoft.
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) (Citation: Endurant CMSTP July 2018)
Atomic Tests
Atomic Test #1 - CMSTP Executing Remote Scriptlet
Adversaries may supply CMSTP.exe with INF files infected with malicious commands
Supported Platforms: windows
auto_generated_guid: 34e63321-9683-496b-bbc1-7566bc55e624
Inputs:
| Name | Description | Type | Default Value |
|---|---|---|---|
| inf_file_path | Path to the INF file | path | PathToAtomicsFolder\T1218.003\src\T1218.003.inf |
Attack Commands: Run with command_prompt!
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cmstp.exe /s "#{inf_file_path}"
Dependencies: Run with powershell!
Description: INF file must exist on disk at specified location (#{inf_file_path})
Check Prereq Commands:
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if (Test-Path "#{inf_file_path}") {exit 0} else {exit 1}
Get Prereq Commands:
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New-Item -Type Directory (split-path "#{inf_file_path}") -ErrorAction ignore | Out-Null
Invoke-WebRequest "https://github.com/redcanaryco/atomic-red-team/raw/master/atomics/T1218.003/src/T1218.003.inf" -OutFile "#{inf_file_path}"
Atomic Test #2 - CMSTP Executing UAC Bypass
Adversaries may invoke cmd.exe (or other malicious commands) by embedding them in the RunPreSetupCommandsSection of an INF file
Supported Platforms: windows
auto_generated_guid: 748cb4f6-2fb3-4e97-b7ad-b22635a09ab0
Inputs:
| Name | Description | Type | Default Value |
|---|---|---|---|
| inf_file_uac | Path to the INF file | path | PathToAtomicsFolder\T1218.003\src\T1218.003_uacbypass.inf |
Attack Commands: Run with command_prompt!
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cmstp.exe /s "#{inf_file_uac}" /au
Dependencies: Run with powershell!
Description: INF file must exist on disk at specified location (#{inf_file_uac})
Check Prereq Commands:
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if (Test-Path "#{inf_file_uac}") {exit 0} else {exit 1}
Get Prereq Commands:
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New-Item -Type Directory (split-path "#{inf_file_uac}") -ErrorAction ignore | Out-Null
Invoke-WebRequest "https://github.com/redcanaryco/atomic-red-team/raw/master/atomics/T1218.003/src/T1218.003_uacbypass.inf" -OutFile "#{inf_file_uac}"