New Root Certificate Installed Via CertMgr.EXE — Sigma Rule

Rule metadata and linked tags

Author: oscd.community, @redcanary, Zach Stanford @svch0st. Source status: test; severity: medium. Source dates: 2023-03-05 / not supplied.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 8c5d5e625bcb15e73567e8fbf7e962f1417a48e20cd444054d3f70d8fe39e9ba

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 Root Certificate Installed Via CertMgr.EXE
id: ff992eac-6449-4c60-8c1d-91c9722a1d48
related:
    - id: 42821614-9264-4761-acfc-5772c3286f76
      type: derived
    - id: 46591fae-7a4c-46ea-aec3-dff5e6d785dc
      type: obsolete
status: test
description: |
    Detects execution of "certmgr" with the "add" flag in order to install a new certificate on the system.
    Adversaries may install a root certificate on a compromised system to avoid warnings when connecting to adversary controlled web servers.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1553.004/T1553.004.md
    - https://securelist.com/to-crypt-or-to-mine-that-is-the-question/86307/
author: oscd.community, @redcanary, Zach Stanford @svch0st
date: 2023-03-05
tags:
    - attack.defense-impairment
    - attack.t1553.004
logsource:
    category: process_creation
    product: windows
detection:
    # Example: CertMgr.exe /add CertificateFileName.cer /s /r localMachine root /all
    selection_img:
        - Image|endswith: '\CertMgr.exe'
        - OriginalFileName: 'CERTMGT.EXE'
    selection_cli:
        CommandLine|contains|all:
            - '/add'
            - 'root'
    condition: all of selection_*
falsepositives:
    - Help Desk or IT may need to manually add a corporate Root CA on occasion. Need to test if GPO push doesn't trigger FP
level: medium

Original YAML and metadata in JSON

False positives

• Help Desk or IT may need to manually add a corporate Root CA on occasion. Need to test if GPO push doesn't trigger FP

Source references

• https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1553.004/T1553.004.md
• https://securelist.com/to-crypt-or-to-mine-that-is-the-question/86307/