huntrule

Windows Registry Defender Exclusions Path Set (Microsoft\Windows Defender\Exclusions)

Identifies registry updates that reference the Windows Defender Exclusions path, indicating potential defense impairment.

FreeUnreviewedSigmamediumv1
title: Windows Registry Defender Exclusions Path Set (Microsoft\Windows Defender\Exclusions)
id: b3824f8f-ca59-4d4a-908a-a38c85d6f721
related:
  - id: 1321dc4e-a1fe-481d-a016-52c45f0c8b4f
    type: derived
  - id: a982fc9c-6333-4ffb-a51d-addb04e8b529
    type: derived
status: test
description: This rule flags registry activity where the target value contains the Windows Defender Exclusions path. Adding exclusions can help an attacker avoid scanning for selected files, processes, or locations, enabling defense impairment. The detection relies on registry_set telemetry and matches the target object string for the Defender Exclusions key path. Common false positives include legitimate administrator configuration changes.
references:
  - https://twitter.com/_nullbind/status/1204923340810543109
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/registry/registry_set/registry_set_defender_exclusions.yml
author: Christian Burkard (Nextron Systems), Huntrule Team
date: 2021-07-06
modified: 2023-08-17
tags:
  - attack.defense-impairment
  - attack.t1685
logsource:
  product: windows
  category: registry_set
detection:
  selection2:
    TargetObject|contains: \Microsoft\Windows Defender\Exclusions
  condition: selection2
falsepositives:
  - Administrator actions
level: medium
license: DRL-1.1

What it detects

This rule flags registry activity where the target value contains the Windows Defender Exclusions path. Adding exclusions can help an attacker avoid scanning for selected files, processes, or locations, enabling defense impairment. The detection relies on registry_set telemetry and matches the target object string for the Defender Exclusions key path. Common false positives include legitimate administrator configuration changes.

Known false positives

  • Administrator actions

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