Suspicious DLL Loaded via CertOC.EXE — Sigma Rule

Rule metadata and linked tags

Author: Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: high. Source dates: 2023-02-15 / 2024-03-05.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 6f1220dbeb50bda747ba80b924520cf5085fe8022b341344c27014065c44daa2

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: Suspicious DLL Loaded via CertOC.EXE
id: 84232095-ecca-4015-b0d7-7726507ee793
related:
    - id: 242301bc-f92f-4476-8718-78004a6efd9f
      type: similar
status: test
description: Detects when a user installs certificates by using CertOC.exe to load the target DLL file.
references:
    - https://twitter.com/sblmsrsn/status/1445758411803480072?s=20
    - https://github.com/elastic/protections-artifacts/commit/746086721fd385d9f5c6647cada1788db4aea95f#diff-fe98e74189873d6df72a15df2eaa0315c59ba9cdaca93ecd68afc4ea09194ef2
    - https://lolbas-project.github.io/lolbas/Binaries/Certoc/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-02-15
modified: 2024-03-05
tags:
    - attack.stealth
    - attack.t1218
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\certoc.exe'
        - OriginalFileName: 'CertOC.exe'
    selection_cli:
        CommandLine|contains|windash: ' -LoadDLL '
    selection_paths:
        CommandLine|contains:
            - '\Appdata\Local\Temp\'
            - '\Desktop\'
            - '\Downloads\'
            - '\Users\Public\'
            - 'C:\Windows\Tasks\'
            - 'C:\Windows\Temp\'
    condition: all of selection_*
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://twitter.com/sblmsrsn/status/1445758411803480072?s=20
• https://github.com/elastic/protections-artifacts/commit/746086721fd385d9f5c6647cada1788db4aea95f#diff-fe98e74189873d6df72a15df2eaa0315c59ba9cdaca93ecd68afc4ea09194ef2
• https://lolbas-project.github.io/lolbas/Binaries/Certoc/