Windows PowerShell execution with uncommon/suspicious parent process

Alerts when PowerShell is started from certain unusual parent processes that commonly indicate abuse.

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windows-powershell-execution-with-uncommon-suspicious-parent-process-754ed792

title: Windows PowerShell execution with uncommon/suspicious parent process
id: f940c984-567f-4f4c-9e74-5fa28ff455d4
related:
  - id: 692f0bec-83ba-4d04-af7e-e884a96059b6
    type: derived
  - id: 754ed792-634f-40ae-b3bc-e0448d33f695
    type: derived
status: test
description: This rule flags process creation events where PowerShell (powershell.exe or pwsh.exe) is launched with a parent process image matching specific web/browser/application service executables (e.g., tomcat, various browsers, httpd/nginx/iis-related components, rundll32, mshta). Attackers often use abnormal parent-child process relationships to blend PowerShell execution into expected application activity or abuse parent processes for script execution. The detection relies on Windows process creation telemetry fields for ParentImage, Image, CommandLine, Description/Product, and OriginalFileName to match PowerShell and constrained parent process patterns.
references:
  - https://speakerdeck.com/heirhabarov/hunting-for-powershell-abuse?slide=26
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_powershell_susp_parent_process.yml
author: Teymur Kheirkhabarov, Harish Segar, Huntrule Team
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
        - /c pwsh
    - Description: Windows PowerShell
    - Product: PowerShell Core 6
    - OriginalFileName:
        - PowerShell.EXE
        - pwsh.dll
  condition: all of selection_*
falsepositives:
  - Other scripts
level: high
license: DRL-1.1

What it detects

This rule flags process creation events where PowerShell (powershell.exe or pwsh.exe) is launched with a parent process image matching specific web/browser/application service executables (e.g., tomcat, various browsers, httpd/nginx/iis-related components, rundll32, mshta). Attackers often use abnormal parent-child process relationships to blend PowerShell execution into expected application activity or abuse parent processes for script execution. The detection relies on Windows process creation telemetry fields for ParentImage, Image, CommandLine, Description/Product, and OriginalFileName to match PowerShell and constrained parent process patterns.

Known false positives

Other scripts

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.