Windows Defender Exclusions Added via PowerShelledit

Identifies modifications to the Windows Defender configuration settings using PowerShell to add exclusions at the folder directory or process level.

Rule type: eql

Rule indices:

  • winlogbeat-*
  • logs-endpoint.events.*
  • logs-windows.*

Severity: medium

Risk score: 47

Runs every: 5m

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Elastic
  • Host
  • Windows
  • Threat Detection
  • Defense Evasion

Version: 2

Rule authors:

  • Elastic

Rule license: Elastic License v2

Investigation guideedit

## Triage and analysis

Detections should be investigated to identify if the activity corresponds to legitimate activity used to put in exceptions for Windows Defender. As this rule detects post-exploitation process activity, investigations into this should be prioritized.

Rule queryedit

process where event.type == "start" and
 (process.name : ("powershell.exe", "pwsh.exe") or process.pe.original_file_name : ("powershell.exe", "pwsh.exe")) and
  process.args : ("*Add-MpPreference*-Exclusion*", "*Set-MpPreference*-Exclusion*")

Framework: MITRE ATT&CKTM