Windows PowerShell sets Microsoft Defender threat severity default actions to Allow/NoAction
Alerts when PowerShell Set-MpPreference sets Defender threat-severity default actions to Allow or NoAction.
- Product
- windows
- Category
- process_creation
- Author
- Matt Anderson (Huntress) (SigmaHQ), DRL 1.1
- Published
- 2025-07-11
- Updated
- 2026-07-31
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 flags process creation events where PowerShell runs Set-MpPreference to change Microsoft Defender threat severity default actions to Allow (including value 6) or NoAction (including value 9). Such configuration changes can reduce Defender’s ability to automatically mitigate threats for specified severity levels. The detection relies on command-line telemetry that includes Set-MpPreference and the relevant default-action parameters and values.
Reporting behind it
- learn.microsoft.comhttps://learn.microsoft.com/en-us/powershell/module/defender/set-mppreference
- learn.microsoft.comhttps://learn.microsoft.com/en-us/windows-hardware/customize/desktop/unattend/security-malware-windows-defender-threatseveritydefaultaction
- research.splunk.comhttps://research.splunk.com/endpoint/7215831c-8252-4ae3-8d43-db588e82f952
- gist.github.comhttps://gist.github.com/Dump-GUY/8daef859f382b895ac6fd0cf094555d2
- thedfirreport.comhttps://thedfirreport.com/2021/10/18/icedid-to-xinglocker-ransomware-in-24-hours/
- github.comhttps://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_defender_default_action_modified.yml
Changelog
v2- v2Candidate ingested via manual entry.2026-07-31
- v1No 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.
title: Windows PowerShell sets Microsoft Defender threat severity default actions to Allow/NoAction
id: afd82cfa-d276-45f3-8ea2-5553b02271fc
related:
- id: 5a9e1b2c-8f7d-4a1e-9b3c-0f6d7e5a4b1f
type: similar
- id: 1e8a9b4d-3c2a-4f9b-8d1e-7c6a5b4f3d2e
type: derived
status: experimental
description: This rule flags process creation events where PowerShell runs Set-MpPreference to change Microsoft Defender threat severity default actions to Allow (including value 6) or NoAction (including value 9). Such configuration changes can reduce Defender’s ability to automatically mitigate threats for specified severity levels. The detection relies on command-line telemetry that includes Set-MpPreference and the relevant default-action parameters and values.
references:
- https://learn.microsoft.com/en-us/powershell/module/defender/set-mppreference
- https://learn.microsoft.com/en-us/windows-hardware/customize/desktop/unattend/security-malware-windows-defender-threatseveritydefaultaction
- https://research.splunk.com/endpoint/7215831c-8252-4ae3-8d43-db588e82f952
- https://gist.github.com/Dump-GUY/8daef859f382b895ac6fd0cf094555d2
- https://thedfirreport.com/2021/10/18/icedid-to-xinglocker-ransomware-in-24-hours/
- https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_defender_default_action_modified.yml
author: Matt Anderson (Huntress), Huntrule Team
date: 2025-07-11
tags:
- attack.defense-impairment
- attack.t1685
logsource:
category: process_creation
product: windows
detection:
selection_cmdlet:
CommandLine|contains: Set-MpPreference
selection_action:
CommandLine|contains:
- -LowThreatDefaultAction
- -ModerateThreatDefaultAction
- -HighThreatDefaultAction
- -SevereThreatDefaultAction
- "-ltdefac "
- "-mtdefac "
- "-htdefac "
- "-stdefac "
selection_value:
CommandLine|contains:
- Allow
- "6"
- NoAction
- "9"
condition: all of selection_*
falsepositives:
- Highly unlikely
level: high
license: DRL-1.1