Suspicious CertReq Command to Download — Sigma Rule

Rule metadata and linked tags

Author: Christian Burkard (Nextron Systems). Source status: experimental; severity: high. Source dates: 2021-11-24 / 2025-10-29.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 901342ae9cc2325212a2d66778210946c15f8c13a237bd23f3334760dd2962d5

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 CertReq Command to Download
id: 4480827a-9799-4232-b2c4-ccc6c4e9e12b
status: experimental
description: |
    Detects a suspicious CertReq execution downloading a file.
    This behavior is often used by attackers to download additional payloads or configuration files.
    Certreq is a built-in Windows utility used to request and retrieve certificates from a certification authority (CA). However, it can be abused by threat actors for malicious purposes.
references:
    - https://lolbas-project.github.io/lolbas/Binaries/Certreq/
author: Christian Burkard (Nextron Systems)
date: 2021-11-24
modified: 2025-10-29
tags:
    - attack.command-and-control
    - attack.t1105
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\certreq.exe'
        - OriginalFileName: 'CertReq.exe'
    selection_cli_flag_post:
        CommandLine|contains|windash: '-Post'
    selection_cli_flag_config:
        CommandLine|contains|windash: '-config'
    selection_cli_http:
        CommandLine|contains: 'http'
    condition: all of selection_*
falsepositives:
    - Unlikely
level: high

Original YAML and metadata in JSON

False positives

• Unlikely

Source references

• https://lolbas-project.github.io/lolbas/Binaries/Certreq/