WDAC Policy File Creation In CodeIntegrity Folder

Status: experimental
Severity: medium
Log source: category file_event, product windows
Author: Andreas Braathen (mnemonic.io)
Source: github.com/SigmaHQ/sigma

Attackers can craft a custom Windows Defender Application Control (WDAC) policy that blocks Endpoint Detection and Response (EDR) components while allowing their own malicious code. The policy is placed in the privileged Windows Code Integrity folder (C:\Windows\System32\CodeIntegrity). Upon reboot, the policy prevents EDR drivers from loading, effectively bypassing security measures and may further enable undetected lateral movement within an Active Directory environment.

Known false positives

May occur legitimately as part of admin activity, but rarely with interactive elevation.

MITRE ATT&CK coverage

Tactic	Techniques
Defense Impairment	`T1685` Disable or Modify Tools

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 11: FileCreate

Rule body

title: WDAC Policy File Creation In CodeIntegrity Folder
id: 121b25f7-b9d6-4b37-afa0-cba317ec52f3
status: experimental
description: |
    Attackers can craft a custom Windows Defender Application Control (WDAC) policy that blocks Endpoint Detection and Response (EDR) components while allowing their own malicious code. The policy is placed in the privileged Windows Code Integrity folder (C:\Windows\System32\CodeIntegrity\). Upon reboot, the policy prevents EDR drivers from loading, effectively bypassing security measures and may further enable undetected lateral movement within an Active Directory environment.
references:
    - https://beierle.win/2024-12-20-Weaponizing-WDAC-Killing-the-Dreams-of-EDR/
    - https://www.virustotal.com/gui/file/d2a4f52a9923336f119a52e531bbb1e66f18322fd8efa9af1a64b94f4d36dc97
author: Andreas Braathen (mnemonic.io)
date: 2025-01-30
tags:
    - attack.defense-impairment
    - attack.t1685
    - detection.threat-hunting
logsource:
    category: file_event
    product: windows
    definition: 'Requirements: By default the file_event log source might not contain the IntegrityLevel of the Process. It should be collected in order to use this rule'
detection:
    selection:
        TargetFilename|contains: ':\Windows\System32\CodeIntegrity\'
        TargetFilename|endswith:
            - '.cip'
            - '.p7b'
        IntegrityLevel: 'High'
    condition: selection
falsepositives:
    - May occur legitimately as part of admin activity, but rarely with interactive elevation.
level: medium

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    TargetFilename|contains: ':\Windows\System32\CodeIntegrity\'
    TargetFilename|endswith:
        - '.cip'
        - '.p7b'
    IntegrityLevel: 'High'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`IntegrityLevel`	eq	`High` corpus 21 (sigma 17, kusto 3, splunk 1)	`field:"IntegrityLevel" kind:eq value:"High"`
`TargetFilename`	ends_with	`.cip` `.p7b`	`field:"TargetFilename" kind:ends_with`
`TargetFilename`	match	`:\Windows\System32\CodeIntegrity\`	`field:"TargetFilename" kind:match value:":\Windows\System32\CodeIntegrity\"`