Windows PowerShell Script Proxy Execution via CL_mutexverifiers.ps1
Alerts on PowerShell being launched with CL_mutexverifiers that proxies additional script execution.
- Product
- windows
- Category
- process_creation
- Author
- Nasreddine Bencherchali (Nextron Systems), oscd.community, Natalia Shornikova, frack113 (SigmaHQ), DRL 1.1
- Published
- 2022-05-21
- Updated
- 2026-07-30
ATT&CK techniques
Defense EvasionRecon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact
What it detects
This rule flags process creation where a signed PowerShell script named CL_mutexverifiers is invoked to proxy execution of additional PowerShell script commands. Attackers can use this kind of script wrapper to stealthily launch secondary PowerShell payloads through an approved, signed script. The detection relies on process creation telemetry capturing the parent PowerShell invocation, the executed PowerShell image, and command-line arguments indicating the wrapped script and temporary path usage.
Reporting behind it
Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.
title: Windows PowerShell Script Proxy Execution via CL_mutexverifiers.ps1
id: c5ba371e-2a28-407f-a31d-6f56b9285242
status: test
description: This rule flags process creation where a signed PowerShell script named CL_mutexverifiers is invoked to proxy execution of additional PowerShell script commands. Attackers can use this kind of script wrapper to stealthily launch secondary PowerShell payloads through an approved, signed script. The detection relies on process creation telemetry capturing the parent PowerShell invocation, the executed PowerShell image, and command-line arguments indicating the wrapped script and temporary path usage.
references:
- https://lolbas-project.github.io/lolbas/Scripts/CL_mutexverifiers/
- https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_powershell_cl_mutexverifiers.yml
author: Nasreddine Bencherchali (Nextron Systems), oscd.community, Natalia Shornikova, frack113, Huntrule Team
date: 2022-05-21
modified: 2023-08-17
tags:
- attack.stealth
- attack.t1216
logsource:
category: process_creation
product: windows
detection:
selection_pwsh:
ParentImage|endswith:
- \powershell.exe
- \pwsh.exe
Image|endswith: \powershell.exe
CommandLine|contains: " -nologo -windowstyle minimized -file "
selection_temp:
CommandLine|contains:
- \AppData\Local\Temp\
- \Windows\Temp\
condition: all of selection_*
falsepositives:
- Unknown
level: medium
license: DRL-1.1
related:
- id: 1e0e1a81-e79b-44bc-935b-ddb9c8006b3d
type: derived