Clear PowerShell History - PowerShell — Sigma Rule

Rule metadata and linked tags

Author: Ilyas Ochkov, Jonhnathan Ribeiro, Daniil Yugoslavskiy, oscd.community. Source status: test; severity: medium. Source dates: 2022-01-25 / 2022-12-02.

{
  "product": "windows",
  "category": "ps_script",
  "definition": "Requirements: Script Block Logging must be enabled"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: a7d884c70b1e2e37e1e1f1e8287712718c63ce5502d0c415344c260354419597

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: Clear PowerShell History - PowerShell
id: 26b692dc-1722-49b2-b496-a8258aa6371d
related:
    - id: dfba4ce1-e0ea-495f-986e-97140f31af2d
      type: derived
status: test
description: Detects keywords that could indicate clearing PowerShell history
references:
    - https://gist.github.com/hook-s3c/7363a856c3cdbadeb71085147f042c1a
author: Ilyas Ochkov, Jonhnathan Ribeiro, Daniil Yugoslavskiy, oscd.community
date: 2022-01-25
modified: 2022-12-02
tags:
    - attack.stealth
    - attack.t1070.003
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    selection1a:
        ScriptBlockText|contains:
            - 'del'
            - 'Remove-Item'
            - 'rm'
    selection1b:
        ScriptBlockText|contains: '(Get-PSReadlineOption).HistorySavePath'
    selection_2:
        ScriptBlockText|contains|all:
            - 'Set-PSReadlineOption'
            - '–HistorySaveStyle'  # not sure if the homoglyph –/- is intended, just checking for both
            - 'SaveNothing'
    selection_3:
        ScriptBlockText|contains|all:
            - 'Set-PSReadlineOption'
            - '-HistorySaveStyle'
            - 'SaveNothing'
    condition: 1 of selection_* or all of selection1*
falsepositives:
    - Legitimate PowerShell scripts
level: medium

Original YAML and metadata in JSON

False positives

• Legitimate PowerShell scripts

Source references

• https://gist.github.com/hook-s3c/7363a856c3cdbadeb71085147f042c1a