New DLL Added to AppCertDlls Registry Key — Sigma Rule

Rule metadata and linked tags

Author: Ilyas Ochkov, oscd.community. Source status: test; severity: medium. Source dates: 2019-10-25 / 2021-11-27.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: e605e26f9afd15dadda4a3b960b06c8dc2b46b6f16b656ff3995513dab7bf02c

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 AppCertDlls Registry Key
id: 6aa1d992-5925-4e9f-a49b-845e51d1de01
status: test
description: |
  Dynamic-link libraries (DLLs) that are specified in the AppCertDLLs value in the Registry key can be abused to obtain persistence and privilege escalation
  by causing a malicious DLL to be loaded and run in the context of separate processes on the computer.
references:
    - http://www.hexacorn.com/blog/2013/01/19/beyond-good-ol-run-key-part-3/
    - https://eqllib.readthedocs.io/en/latest/analytics/14f90406-10a0-4d36-a672-31cabe149f2f.html
author: Ilyas Ochkov, oscd.community
date: 2019-10-25
modified: 2021-11-27
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.t1546.009
logsource:
    category: registry_event
    product: windows
detection:
    selection:
        # Sysmon gives us HKLM\SYSTEM\CurrentControlSet\.. if ControlSetXX is the selected one
        - TargetObject: 'HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\AppCertDlls'
        # key rename
        - NewName: 'HKLM\SYSTEM\CurentControlSet\Control\Session Manager\AppCertDlls'
    condition: selection
falsepositives:
    - Unknown
level: medium

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• http://www.hexacorn.com/blog/2013/01/19/beyond-good-ol-run-key-part-3/
• https://eqllib.readthedocs.io/en/latest/analytics/14f90406-10a0-4d36-a672-31cabe149f2f.html