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Detection rules › Sigma

Suspicious Uninstall of Windows Defender Feature via PowerShell

Status
experimental
Severity
high
Log source
product windows, category process_creation
Author
yxinmiracle
Source
github.com/SigmaHQ/sigma

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.

MITRE ATT&CK coverage

TacticTechniques
Defense ImpairmentT1685 Disable or Modify Tools

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation

Rule body yaml

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

Stages and Predicates

Stage 0: condition

all of selection_*

Stage 1: selection_img

selection_img:
    - Image|endswith:
          - '\powershell_ise.exe'
          - '\powershell.exe'
          - '\pwsh.exe'
    - OriginalFileName:
          - 'PowerShell_ISE.EXE'
          - 'PowerShell.EXE'
          - 'pwsh.dll'

Stage 2: selection_cli_uninstall

selection_cli_uninstall:
    CommandLine|contains:
        - 'Uninstall-WindowsFeature'
        - 'Remove-WindowsFeature'

Stage 3: selection_cli_defender_feature

selection_cli_defender_feature:
    CommandLine|contains: 'Windows-Defender'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
CommandLinematch
  • Remove-WindowsFeature
  • Uninstall-WindowsFeature
  • Windows-Defender corpus 2 (sigma 1, splunk 1)
Imageends_with
  • \powershell.exe corpus 182 (sigma 182)
  • \powershell_ise.exe corpus 41 (sigma 41)
  • \pwsh.exe corpus 168 (sigma 168)
OriginalFileNameeq
  • PowerShell.EXE corpus 120 (sigma 84, splunk 30, elastic 6)
  • PowerShell_ISE.EXE corpus 51 (splunk 30, sigma 18, elastic 3)
  • pwsh.dll corpus 112 (sigma 79, splunk 30, elastic 3)