Suspicious PowerShell Parent Process — Sigma Rule

Rule metadata and linked tags

Author: Teymur Kheirkhabarov, Harish Segar. Source status: test; severity: high. Source dates: 2020-03-20 / 2023-02-04.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 65c6e32685197796a5b3225a331afd375bd022cb5d772699482aed96bca792b5

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: Suspicious PowerShell Parent Process
id: 754ed792-634f-40ae-b3bc-e0448d33f695
related:
    - id: 692f0bec-83ba-4d04-af7e-e884a96059b6
      type: derived
status: test
description: Detects a suspicious or uncommon parent processes of PowerShell
references:
    - https://speakerdeck.com/heirhabarov/hunting-for-powershell-abuse?slide=26
author: Teymur Kheirkhabarov, Harish Segar
date: 2020-03-20
modified: 2023-02-04
tags:
    - attack.execution
    - attack.t1059.001
logsource:
    category: process_creation
    product: windows
detection:
    selection_parent:
        - ParentImage|contains: 'tomcat'
        - ParentImage|endswith:
              - '\amigo.exe'
              - '\browser.exe'
              - '\chrome.exe'
              - '\firefox.exe'
              - '\httpd.exe'
              - '\iexplore.exe'
              - '\jbosssvc.exe'
              - '\microsoftedge.exe'
              - '\microsoftedgecp.exe'
              - '\MicrosoftEdgeSH.exe'
              - '\mshta.exe'
              - '\nginx.exe'
              - '\outlook.exe'
              - '\php-cgi.exe'
              - '\regsvr32.exe'
              - '\rundll32.exe'
              - '\safari.exe'
              - '\services.exe'
              - '\sqlagent.exe'
              - '\sqlserver.exe'
              - '\sqlservr.exe'
              - '\vivaldi.exe'
              - '\w3wp.exe'
    selection_powershell:
        - Image|endswith:
              - '\powershell.exe'
              - '\pwsh.exe'
        - CommandLine|contains:
              - '/c powershell'  # FPs with sub processes that contained "powershell" somewhere in the command line
              - '/c pwsh'
        - Description: 'Windows PowerShell'
        - Product: 'PowerShell Core 6'
        - OriginalFileName:
              - 'PowerShell.EXE'
              - 'pwsh.dll'
    condition: all of selection_*
falsepositives:
    - Other scripts
level: high

Original YAML and metadata in JSON

False positives

• Other scripts

Source references

• https://speakerdeck.com/heirhabarov/hunting-for-powershell-abuse?slide=26