Sigma rule: Curl.EXE Execution With Custom UserAgent

Rule

Title

Curl.EXE Execution With Custom UserAgent

Status

test

Level

medium

Author

frack113

Date

2022-01-23

Modified

2023-02-21

File

rules-threat-hunting/windows/process_creation/proc_creation_win_curl_useragent.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects execution of curl.exe with custom useragent options

Log source

product

windows

category

process_creation

Detection

selection_curl:
    - Image|endswith: '\curl.exe'
    - Product: 'The curl executable'
selection_opt:
    CommandLine|contains:
        - ' -A '
        - ' --user-agent '
condition: all of selection_*

False positives (as the rule lists them)

• Scripts created by developers and admins
• Administrative activity

Tags

• attack.command-and-control
• attack.t1071.001
• detection.threat-hunting

MITRE ATT&CK ids this rule names

• T1071.001

References

• https://curl.se/docs/manpage.html
• https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1071.001/T1071.001.md#atomic-test-2---malicious-user-agents---cmd

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