Change Winevt Channel Access Permission Via Registry — Sigma Rule

Rule metadata and linked tags

Author: frack113. Source status: test; severity: high. Source dates: 2022-09-17 / 2024-03-25.

{
  "category": "registry_set",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 6b47af48cd92b796610088601ba148d1d1304b4eea9bb811f0636a516b80549d

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Change Winevt Channel Access Permission Via Registry
id: 7d9263bd-dc47-4a58-bc92-5474abab390c
status: test
description: Detects tampering with the "ChannelAccess" registry key in order to change access to Windows event channel.
references:
    - https://app.any.run/tasks/77b2e328-8f36-46b2-b2e2-8a80398217ab/
    - https://learn.microsoft.com/en-us/windows/win32/api/winevt/
    - https://itconnect.uw.edu/tools-services-support/it-systems-infrastructure/msinf/other-help/understanding-sddl-syntax/
author: frack113
date: 2022-09-17
modified: 2024-03-25
tags:
    - attack.defense-impairment
    - attack.t1685.001
logsource:
    category: registry_set
    product: windows
detection:
    selection:
        TargetObject|contains: '\Microsoft\Windows\CurrentVersion\WINEVT\Channels\'
        TargetObject|endswith: '\ChannelAccess'
        # Add more interesting combinations if you found them
        Details|contains:
            - '(A;;0x1;;;LA)' # Local administrator having GENERIC ALL
            - '(A;;0x1;;;SY)' # Local System having GENERIC ALL
            - '(A;;0x5;;;BA)' # Built-in administrators having GENERIC ALL and  GENERIC WRITE
    filter_main_trustedinstaller:
        Image: 'C:\Windows\servicing\TrustedInstaller.exe'
    filter_main_tiworker:
        Image|startswith: 'C:\Windows\WinSxS\'
        Image|endswith: '\TiWorker.exe'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://app.any.run/tasks/77b2e328-8f36-46b2-b2e2-8a80398217ab/
• https://learn.microsoft.com/en-us/windows/win32/api/winevt/
• https://itconnect.uw.edu/tools-services-support/it-systems-infrastructure/msinf/other-help/understanding-sddl-syntax/