PowerShell Set-Acl On Windows Folder - PsScript — Sigma Rule

Rule metadata and linked tags

Author: frack113, Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: high. Source dates: 2023-07-18 / not supplied.

{
  "product": "windows",
  "category": "ps_script",
  "definition": "bade5735-5ab0-4aa7-a642-a11be0e40872"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: e8a88704647a05eb242b93287958690af62976ed8b0e81c009bb780ba43cc4a8

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: PowerShell Set-Acl On Windows Folder - PsScript
id: 3bf1d859-3a7e-44cb-8809-a99e066d3478
related:
    - id: cae80281-ef23-44c5-873b-fd48d2666f49 # PsScript Low
      type: derived
    - id: 0944e002-e3f6-4eb5-bf69-3a3067b53d73 # ProcCreation Susp
      type: derived
    - id: bdeb2cff-af74-4094-8426-724dc937f20a # ProcCreation Low
      type: derived
status: test
description: Detects PowerShell scripts to set the ACL to a file in the Windows folder
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/74438b0237d141ee9c99747976447dc884cb1a39/atomics/T1505.005/T1505.005.md
    - https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.security/set-acl?view=powershell-5.1
author: frack113, Nasreddine Bencherchali (Nextron Systems)
date: 2023-07-18
tags:
    - attack.defense-impairment
    - attack.t1222
logsource:
    product: windows
    category: ps_script
    definition: bade5735-5ab0-4aa7-a642-a11be0e40872
detection:
    selection_cmdlet:
        ScriptBlockText|contains|all:
            - 'Set-Acl '
            - '-AclObject '
    selection_paths:
        # Note: Add more suspicious paths
        ScriptBlockText|contains:
            - '-Path "C:\Windows'
            - '-Path "C:/Windows'
            - "-Path 'C:\\Windows"
            - "-Path 'C:/Windows"
            - '-Path C:\\Windows'
            - '-Path C:/Windows'
            - '-Path $env:windir'
            - '-Path "$env:windir'
            - "-Path '$env:windir"
    selection_permissions:
        # Note: Add more suspicious permissions
        ScriptBlockText|contains:
            - 'FullControl'
            - 'Allow'
    condition: all of selection_*
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://github.com/redcanaryco/atomic-red-team/blob/74438b0237d141ee9c99747976447dc884cb1a39/atomics/T1505.005/T1505.005.md
• https://learn.microsoft.com/en-us/powershell/module/microsoft.powershell.security/set-acl?view=powershell-5.1