Suspicious Uninstall of Windows Defender Feature via PowerShell — Sigma Rule

Rule metadata and linked tags

Author: yxinmiracle. Source status: experimental; severity: high. Source dates: 2025-08-22 / not supplied.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 16ab1d3888d5bc540e30412a97059ca9fd9c6bbb607bd2f87decb12b8488168a

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 Uninstall of Windows Defender Feature via PowerShell
id: c443012c-7928-43bf-ac20-7eda5efe61ad
status: experimental
description: |
    Detects the use of PowerShell with Uninstall-WindowsFeature or Remove-WindowsFeature cmdlets to disable or remove the Windows Defender GUI feature, a common technique used by adversaries to evade defenses.
references:
    - https://learn.microsoft.com/en-us/powershell/module/microsoft.windows.servermanager.migration/uninstall-windowsfeature
    - https://thedfirreport.com/2023/04/03/malicious-iso-file-leads-to-domain-wide-ransomware
author: yxinmiracle
date: 2025-08-22
tags:
    - attack.defense-impairment
    - attack.t1685
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith:
              - '\powershell_ise.exe'
              - '\powershell.exe'
              - '\pwsh.exe'
        - OriginalFileName:
              - 'PowerShell_ISE.EXE'
              - 'PowerShell.EXE'
              - 'pwsh.dll'
    selection_cli_uninstall:
        CommandLine|contains:
            - 'Uninstall-WindowsFeature'
            - 'Remove-WindowsFeature' # Only supported in Windows Server 2008 R2 and Windows 2012 R2
    selection_cli_defender_feature:
        CommandLine|contains: 'Windows-Defender'
    condition: all of selection_*
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://learn.microsoft.com/en-us/powershell/module/microsoft.windows.servermanager.migration/uninstall-windowsfeature
• https://thedfirreport.com/2023/04/03/malicious-iso-file-leads-to-domain-wide-ransomware