New DLL Added to AppInit_DLLs Registry Key — Sigma Rule

Rule metadata and linked tags

Author: Ilyas Ochkov, oscd.community, Tim Shelton. Source status: test; severity: medium. Source dates: 2019-10-25 / 2022-12-25.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 681216dd8a18ac1c1a39a097260133b08e11788403f75f540f389b8df4fe5b35

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: New DLL Added to AppInit_DLLs Registry Key
id: 4f84b697-c9ed-4420-8ab5-e09af5b2345d
status: test
description: DLLs that are specified in the AppInit_DLLs value in the Registry key HKLM\Software\Microsoft\Windows NT\CurrentVersion\Windows are loaded by user32.dll into every process that loads user32.dll
references:
    - https://eqllib.readthedocs.io/en/latest/analytics/822dc4c5-b355-4df8-bd37-29c458997b8f.html
author: Ilyas Ochkov, oscd.community, Tim Shelton
date: 2019-10-25
modified: 2022-12-25
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.t1546.010
logsource:
    category: registry_event
    product: windows
detection:
    selection:
        - TargetObject|endswith:
              - '\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows\AppInit_Dlls'
              - '\SOFTWARE\Wow6432Node\Microsoft\Windows NT\CurrentVersion\Windows\AppInit_Dlls'
        # Key Rename
        - NewName|endswith:
              - '\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Windows\AppInit_Dlls'
              - '\SOFTWARE\Wow6432Node\Microsoft\Windows NT\CurrentVersion\Windows\AppInit_Dlls'
    filter:
        Details: '(Empty)'
    condition: selection and not filter
falsepositives:
    - Unknown
level: medium

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://eqllib.readthedocs.io/en/latest/analytics/822dc4c5-b355-4df8-bd37-29c458997b8f.html