PowerShell Downgrade Attack - PowerShell — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems), Lee Holmes (idea), Harish Segar (improvements). Source status: test; severity: medium. Source dates: 2017-03-22 / 2023-10-27.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 43c17de0d8acb54fa812238b22be8ffde481e75ed512ef4904eee0bdcf762708

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: PowerShell Downgrade Attack - PowerShell
id: 6331d09b-4785-4c13-980f-f96661356249
status: test
description: Detects PowerShell downgrade attack by comparing the host versions with the actually used engine version 2.0
references:
    - http://www.leeholmes.com/blog/2017/03/17/detecting-and-preventing-powershell-downgrade-attacks/
author: Florian Roth (Nextron Systems), Lee Holmes (idea), Harish Segar (improvements)
date: 2017-03-22
modified: 2023-10-27
tags:
    - attack.execution
    - attack.t1059.001
logsource:
    product: windows
    category: ps_classic_start
detection:
    selection:
        Data|contains: 'EngineVersion=2.'
    filter_main:
        Data|contains: 'HostVersion=2.'
    condition: selection and not filter_main
falsepositives:
    - Unknown
level: medium

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• http://www.leeholmes.com/blog/2017/03/17/detecting-and-preventing-powershell-downgrade-attacks/