Windows: CertOC.exe Loading a DLL from User-Writable Paths via -LoadDLL

Alerts on CertOC.exe using -LoadDLL with DLLs from temp/user-writable directories on Windows.

FreeReviewedSigma · High · v2

Product: windows
Category: process_creation
Author: Nasreddine Bencherchali (Nextron Systems) (SigmaHQ), DRL 1.1
Published: 2023-02-15
Updated: 2026-07-31

ATT&CK techniques

Defense Evasion

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
- T1218System Binary Proxy Execution
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule identifies executions of CertOC.exe where the command line includes the -LoadDLL argument and the target DLL is referenced from common user-writable or staging locations. Using CertOC.exe to load a DLL can support stealthy execution by proxying library loads through a signed Microsoft-signed utility. The detection relies on Windows process creation telemetry, specifically the process image/original file name, the command line containing -LoadDLL, and the presence of suspicious file paths in the command line.

Reporting behind it

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Windows: CertOC.exe Loading a DLL from User-Writable Paths via -LoadDLL

Pivot detection · T1218 · 9 related

Changelog

v2
Candidate ingested via manual entry.2026-07-31
v1
No changelog recorded for this version.2026-07-30

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

windows-certoc-exe-loading-dll-from-user-writable-paths-84232095

title: "Windows: CertOC.exe Loading a DLL from User-Writable Paths via -LoadDLL"
id: 9f204adf-0823-4874-9b2e-f8155012453f
related:
  - id: 242301bc-f92f-4476-8718-78004a6efd9f
    type: similar
  - id: 84232095-ecca-4015-b0d7-7726507ee793
    type: derived
status: test
description: This rule identifies executions of CertOC.exe where the command line includes the -LoadDLL argument and the target DLL is referenced from common user-writable or staging locations. Using CertOC.exe to load a DLL can support stealthy execution by proxying library loads through a signed Microsoft-signed utility. The detection relies on Windows process creation telemetry, specifically the process image/original file name, the command line containing -LoadDLL, and the presence of suspicious file paths in the command line.
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/
  - https://github.com/SigmaHQ/sigma/blob/master/rules/windows/process_creation/proc_creation_win_certoc_load_dll_susp_locations.yml
author: Nasreddine Bencherchali (Nextron Systems), Huntrule Team
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
license: DRL-1.1

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