Execute Code with Pester.bat as Parent — Sigma Rule

Rule metadata and linked tags

Author: frack113, Nasreddine Bencherchali. Source status: test; severity: medium. Source dates: 2022-08-20 / not supplied.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 93f1cee82fd6e6cde3fd68887fa168940434f18d9ef10b522d9b01b9f3800e63

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: Execute Code with Pester.bat as Parent
id: 18988e1b-9087-4f8a-82fe-0414dce49878
related:
    - id: 59e938ff-0d6d-4dc3-b13f-36cc28734d4e
      type: similar
status: test
description: Detects code execution via Pester.bat (Pester - Powershell Modulte for testing)
references:
    - https://twitter.com/Oddvarmoe/status/993383596244258816
    - https://twitter.com/_st0pp3r_/status/1560072680887525378
author: frack113, Nasreddine Bencherchali
date: 2022-08-20
tags:
    - attack.execution
    - attack.stealth
    - attack.t1059.001
    - attack.t1216
logsource:
    category: process_creation
    product: windows
detection:
    selection_module:
        ParentImage|endswith:
            - '\powershell.exe'
            - '\pwsh.exe'
        ParentCommandLine|contains: '\WindowsPowerShell\Modules\Pester\'
    selection_cli:
        ParentCommandLine|contains:
            - '{ Invoke-Pester -EnableExit ;'
            - '{ Get-Help "'
    condition: all of selection_*
falsepositives:
    - Legitimate use of Pester for writing tests for Powershell scripts and modules
level: medium

Original YAML and metadata in JSON

False positives

• Legitimate use of Pester for writing tests for Powershell scripts and modules

Source references

• https://twitter.com/Oddvarmoe/status/993383596244258816
• https://twitter.com/_st0pp3r_/status/1560072680887525378