Sigma rule: Suspicious CertReq Command to Download

Rule

Title

Suspicious CertReq Command to Download

Status

experimental

Level

high

Author

Christian Burkard (Nextron Systems)

Date

2021-11-24

Modified

2025-10-29

File

rules/windows/process_creation/proc_creation_win_certreq_download.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

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.

Log source

product

windows

category

process_creation

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_*

False positives (as the rule lists them)

• Unlikely

Tags

• attack.command-and-control
• attack.t1105

MITRE ATT&CK ids this rule names

• T1105

References

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

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_certreq_download.yml