Curl Web Request With Possible Custom User-Agent (via process_creation)

title: Curl Web Request With Possible Custom User-Agent (via process_creation)
id: 24c8ddce-bc50-5664-97d8-c6714e507307
status: stable
description: This rule detects execution of "curl.exe" with a potential custom "User-Agent". Adversaries can abuse this to download or exfiltrate data via "curl" to a domain that only accept specific "User-Agent" strings
references:
    - https://labs.withsecure.com/publications/fin7-target-veeam-servers
    - https://github.com/WithSecureLabs/iocs/blob/344203de742bb7e68bd56618f66d34be95a9f9fc/FIN7VEEAM/iocs.csv
author: Huntrule Team
date: 2026-03-15
tags:
    - attack.execution
    - attack.command-and-control
    - attack.t1105
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\curl.exe'
        - OriginalFileName: 'curl.exe'
    selection_header_flag_1:
        CommandLine|re: '\s-H\s'
    selection_header_flag_2:
        CommandLine|contains: '--header'
    selection_user_agent:
        CommandLine|contains: 'User-Agent:'
    condition: selection_img and 1 of selection_header_* and selection_user_agent
falsepositives:
    - Unknown
level: medium
regression_tests_path: regression_data/rules/windows/process_creation/proc_creation_win_curl_custom_user_agent/info.yml