PowerShell Tamper: Set-MpPreference disables Windows Defender scanning and protections

Flags PowerShell attempts to alter Windows Defender preferences using Set-MpPreference with Allow-style disable/default-action parameters.

FreeReviewedSigma · High · v2

Product: windows
Category: ps_classic_provider_start
Author: frack113, Nasreddine Bencherchali (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2021-06-07
Updated: 2026-07-31

Analysis Detection

ATT&CK techniques

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule identifies PowerShell activity starting a classic provider that uses Set-MpPreference to set Windows Defender settings to allow or disable multiple security features. Attackers may use these configuration changes to reduce detection and prevention coverage by turning off scanning, monitoring, and related protections or forcing default actions to allow threats. The detection relies on telemetry capturing PowerShell provider start events where the Data field contains Set-MpPreference and specific disabling or allow-related parameter values.

Reporting behind it

Related detections9 linkedT1685 — drag to rearrange

Malicious Vulnerable Driver Service Creation for BYOVD (via process_creation)

Malicious Microsoft Defender Disabled via Registry DisableAntiSpyware (via process_creation)

Suspicious Termination of Defender Tray Process via Taskkill

Malicious Windows Defender Disablement via MpCmdRun RemoveDefinitions

Malicious Unsigned VIB Installation on ESXi Host via esxcli (via process_creation)

Suspicious In-Memory PowerShell Execution from Web Server via Automation Assembly (via image_load)

Malicious EDR Evasion Driver Load from AnyDesk Directory via k.sys (via image_load)

Malicious Zemana Vulnerable Driver Load for EDR Termination (via image_load)

Suspicious EDRKillShifter Vulnerable Driver Load from User Temp Directory (via image_load)

PowerShell Tamper: Set-MpPreference disables Windows Defender scanning and protections

Pivot detection · T1685 · 9 related

Changelog

v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

powershell-tampering-with-windows-defender-via-set-mppreference-allow-options-ec19ebab

title: "PowerShell Tamper: Set-MpPreference disables Windows Defender scanning and protections"
id: dd09a83b-dde6-45b0-9a74-8cf74389ad5f
related:
  - id: 14c71865-6cd3-44ae-adaa-1db923fae5f2
    type: similar
  - id: ec19ebab-72dc-40e1-9728-4c0b805d722c
    type: derived
status: test
description: This rule identifies PowerShell activity starting a classic provider that uses Set-MpPreference to set Windows Defender settings to allow or disable multiple security features. Attackers may use these configuration changes to reduce detection and prevention coverage by turning off scanning, monitoring, and related protections or forcing default actions to allow threats. The detection relies on telemetry capturing PowerShell provider start events where the Data field contains Set-MpPreference and specific disabling or allow-related parameter values.
references:
  - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1562.001/T1562.001.md
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/powershell/powershell_classic/posh_pc_tamper_windows_defender_set_mp.yml
author: frack113, Nasreddine Bencherchali (Nextron Systems), Huntrule Team
date: 2021-06-07
modified: 2024-01-02
tags:
  - attack.defense-impairment
  - attack.t1685
logsource:
  product: windows
  category: ps_classic_provider_start
detection:
  selection_set_mppreference:
    Data|contains: Set-MpPreference
  selection_options_bool_allow:
    Data|contains:
      - -dbaf $true
      - -dbaf 1
      - -dbm $true
      - -dbm 1
      - -dips $true
      - -dips 1
      - -DisableArchiveScanning $true
      - -DisableArchiveScanning 1
      - -DisableBehaviorMonitoring $true
      - -DisableBehaviorMonitoring 1
      - -DisableBlockAtFirstSeen $true
      - -DisableBlockAtFirstSeen 1
      - -DisableCatchupFullScan $true
      - -DisableCatchupFullScan 1
      - -DisableCatchupQuickScan $true
      - -DisableCatchupQuickScan 1
      - -DisableIntrusionPreventionSystem $true
      - -DisableIntrusionPreventionSystem 1
      - -DisableIOAVProtection $true
      - -DisableIOAVProtection 1
      - -DisableRealtimeMonitoring $true
      - -DisableRealtimeMonitoring 1
      - -DisableRemovableDriveScanning $true
      - -DisableRemovableDriveScanning 1
      - -DisableScanningMappedNetworkDrivesForFullScan $true
      - -DisableScanningMappedNetworkDrivesForFullScan 1
      - -DisableScanningNetworkFiles $true
      - -DisableScanningNetworkFiles 1
      - -DisableScriptScanning $true
      - -DisableScriptScanning 1
      - -MAPSReporting $false
      - -MAPSReporting 0
      - -drdsc $true
      - -drdsc 1
      - -drtm $true
      - -drtm 1
      - -dscrptsc $true
      - -dscrptsc 1
      - -dsmndf $true
      - -dsmndf 1
      - -dsnf $true
      - -dsnf 1
      - -dss $true
      - -dss 1
  selection_options_actions_func:
    Data|contains:
      - HighThreatDefaultAction Allow
      - htdefac Allow
      - LowThreatDefaultAction Allow
      - ltdefac Allow
      - ModerateThreatDefaultAction Allow
      - mtdefac Allow
      - SevereThreatDefaultAction Allow
      - stdefac Allow
  condition: selection_set_mppreference and 1 of selection_options_*
falsepositives:
  - Legitimate PowerShell scripts that disable Windows Defender for troubleshooting purposes. Must be investigated.
level: high
license: DRL-1.1

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