HackTool - CrackMapExec PowerShell Obfuscation — Sigma Rule

Rule metadata and linked tags

Author: Thomas Patzke. Source status: test; severity: high. Source dates: 2020-05-22 / 2023-02-21.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 2930e5798428d3c325c19393d148906e2edf87c868aac0ea2c2b1eeb4605164a

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: HackTool - CrackMapExec PowerShell Obfuscation
id: 6f8b3439-a203-45dc-a88b-abf57ea15ccf
status: test
description: The CrachMapExec pentesting framework implements a PowerShell obfuscation with some static strings detected by this rule.
references:
    - https://github.com/byt3bl33d3r/CrackMapExec
    - https://github.com/byt3bl33d3r/CrackMapExec/blob/0a49f75347b625e81ee6aa8c33d3970b5515ea9e/cme/helpers/powershell.py#L242
author: Thomas Patzke
date: 2020-05-22
modified: 2023-02-21
tags:
    - attack.execution
    - attack.stealth
    - attack.t1059.001
    - attack.t1027.005
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith:
              - '\powershell.exe'
              - '\pwsh.exe'
        - OriginalFileName:
              - 'PowerShell.EXE'
              - 'pwsh.dll'
    selection_cli:
        CommandLine|contains:
            - 'join*split'
            # Line 343ff
            - '( $ShellId[1]+$ShellId[13]+''x'')'
            - '( $PSHome[*]+$PSHOME[*]+'
            - '( $env:Public[13]+$env:Public[5]+''x'')'
            - '( $env:ComSpec[4,*,25]-Join'''')'
            - '[1,3]+''x''-Join'''')'
    condition: all of selection_*
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://github.com/byt3bl33d3r/CrackMapExec
• https://github.com/byt3bl33d3r/CrackMapExec/blob/0a49f75347b625e81ee6aa8c33d3970b5515ea9e/cme/helpers/powershell.py#L242