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Detection rules › Sigma

Windows Defender Exclusion List Modified

Status
test
Severity
medium
Log source
product windows, service security
Author
@BarryShooshooga
Source
github.com/SigmaHQ/sigma

Detects modifications to the Windows Defender exclusion registry key. This could indicate a potentially suspicious or even malicious activity by an attacker trying to add a new exclusion in order to bypass security.

MITRE ATT&CK coverage

TacticTechniques
Defense ImpairmentT1685 Disable or Modify Tools

Event coverage

ProviderEventTitle
Security-AuditingEvent ID 4657A registry value was modified.

Rule body yaml

title: Windows Defender Exclusion List Modified
id: 46a68649-f218-4f86-aea1-16a759d81820
related:
    - id: e9c8808f-4cfb-4ba9-97d4-e5f3beaa244d
      type: derived
    - id: a33f8808-2812-4373-ae95-8cfb82134978
      type: derived
status: test
description: |
    Detects modifications to the Windows Defender exclusion registry key. This could indicate a potentially suspicious or even malicious activity by an attacker trying to add a new exclusion in order to bypass security.
references:
    - https://www.bleepingcomputer.com/news/security/gootkit-malware-bypasses-windows-defender-by-setting-path-exclusions/
author: '@BarryShooshooga'
date: 2019-10-26
modified: 2023-11-11
tags:
    - attack.defense-impairment
    - attack.t1685
logsource:
    product: windows
    service: security
    definition: 'Requirements: Audit Policy : Security Settings/Local Policies/Audit Policy, Registry System Access Control (SACL): Auditing/User'
detection:
    selection:
        EventID: 4657 # A registry value was modified.
        ObjectName|contains: '\Microsoft\Windows Defender\Exclusions\'
    condition: selection
falsepositives:
    - Intended exclusions by administrators
level: medium

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
    EventID: 4657
    ObjectName|contains: '\Microsoft\Windows Defender\Exclusions\'

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
ObjectNamematch
  • \Microsoft\Windows Defender\Exclusions\ corpus 2 (sigma 2)