Windows curl.exe SOCKS Proxy and .onion Command-Line Execution
Alerts on Windows curl.exe being run with Tor SOCKS proxy URIs and .onion targets in the command line.
- Product
- windows
- Category
- process_creation
- Author
- Arda Buyukkaya (EclecticIQ) (SigmaHQ), DRL 1.1
- Published
- 2025-02-11
- Updated
- 2026-07-31
ATT&CK techniques
Execution → C2Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
Exfiltration
Impact
What it detects
This rule flags Windows process creation events where curl.exe is executed with command-line arguments indicating SOCKS proxy usage (socks5h://, socks5://, socks4a://) and also containing .onion in the same command line. Attackers may leverage curl with SOCKS proxies to reach hidden services and obfuscate network paths for command-and-control or payload retrieval. Telemetry required is Windows process creation data including the full image path and command-line string.
Reporting behind it
- blog.eclecticiq.comhttps://blog.eclecticiq.com/sandworm-apt-targets-ukrainian-users-with-trojanized-microsoft-kms-activation-tools-in-cyber-espionage-campaigns
- github.comhttps://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2025/Malware/proc_creation_win_malware_kalambur_curl_socks_tor.yml
Changelog
v5- v5Candidate ingested via manual entry.2026-07-31
- v4Candidate ingested via manual entry.2026-07-31
- v3Candidate ingested via manual entry.2026-07-31
- v2Candidate ingested via manual entry.2026-07-31
- v1No 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.
title: Windows curl.exe SOCKS Proxy and .onion Command-Line Execution
id: 173dfd3a-a09a-4562-9e3c-4e5917dfeae6
status: experimental
description: This rule flags Windows process creation events where curl.exe is executed with command-line arguments indicating SOCKS proxy usage (socks5h://, socks5://, socks4a://) and also containing .onion in the same command line. Attackers may leverage curl with SOCKS proxies to reach hidden services and obfuscate network paths for command-and-control or payload retrieval. Telemetry required is Windows process creation data including the full image path and command-line string.
references:
- https://blog.eclecticiq.com/sandworm-apt-targets-ukrainian-users-with-trojanized-microsoft-kms-activation-tools-in-cyber-espionage-campaigns
- https://github.com/SigmaHQ/sigma/blob/master/rules-emerging-threats/2025/Malware/proc_creation_win_malware_kalambur_curl_socks_tor.yml
author: Arda Buyukkaya (EclecticIQ), Huntrule Team
date: 2025-02-11
tags:
- attack.execution
- attack.command-and-control
- attack.t1090
- attack.t1573
- attack.t1071.001
- attack.t1059.001
- attack.s0183
- detection.emerging-threats
logsource:
category: process_creation
product: windows
detection:
selection_img:
Image|endswith: \curl.exe
selection_socks:
CommandLine|contains:
- socks5h://
- socks5://
- socks4a://
selection_onion:
CommandLine|contains: .onion
condition: all of selection_*
falsepositives:
- Unlikely
level: high
license: DRL-1.1
related:
- id: e99375eb-3ee0-407a-9f90-79569cc6a01c
type: derived