Shell Open Registry Keys Manipulation — Sigma Rule

Rule metadata and linked tags

Author: Christian Burkard (Nextron Systems). Source status: test; severity: high. Source dates: 2021-08-30 / 2022-01-13.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: dad24734711d2b2d78103c57e3cb12cd468e02c758989b5b0896f37803e5cdad

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: Shell Open Registry Keys Manipulation
id: 152f3630-77c1-4284-bcc0-4cc68ab2f6e7
related:
    - id: dd3ee8cc-f751-41c9-ba53-5a32ed47e563
      type: similar
status: test
description: Detects the shell open key manipulation (exefile and ms-settings) used for persistence and the pattern of UAC Bypass using fodhelper.exe, computerdefaults.exe, slui.exe via registry keys (e.g. UACMe 33 or 62)
references:
    - https://github.com/hfiref0x/UACME
    - https://winscripting.blog/2017/05/12/first-entry-welcome-and-uac-bypass/
    - https://github.com/RhinoSecurityLabs/Aggressor-Scripts/tree/master/UACBypass
    - https://tria.ge/211119-gs7rtshcfr/behavioral2 [Lokibot sample from Nov 2021]
author: Christian Burkard (Nextron Systems)
date: 2021-08-30
modified: 2022-01-13
tags:
    - attack.persistence
    - attack.privilege-escalation
    - attack.t1548.002
    - attack.t1546.001
logsource:
    category: registry_event
    product: windows
detection:
    selection1:
        EventType: SetValue
        TargetObject|endswith: 'Classes\ms-settings\shell\open\command\SymbolicLinkValue'
        Details|contains: '\Software\Classes\{'
    selection2:
        TargetObject|endswith: 'Classes\ms-settings\shell\open\command\DelegateExecute'
    selection3:
        EventType: SetValue
        TargetObject|endswith:
            - 'Classes\ms-settings\shell\open\command\(Default)'
            - 'Classes\exefile\shell\open\command\(Default)'
    filter_sel3:
        Details: '(Empty)'
    condition: selection1 or selection2 or (selection3 and not filter_sel3)
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://github.com/hfiref0x/UACME
• https://winscripting.blog/2017/05/12/first-entry-welcome-and-uac-bypass/
• https://github.com/RhinoSecurityLabs/Aggressor-Scripts/tree/master/UACBypass
• https://tria.ge/211119-gs7rtshcfr/behavioral2 [Lokibot sample from Nov 2021]