Detection rules › Sigma
Kalambur Backdoor Curl TOR SOCKS Proxy Execution
Detects the execution of the "curl.exe" command, referencing "SOCKS" and ".onion" domains, which could be indicative of Kalambur backdoor activity.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Execution | T1059.001 Command and Scripting Interpreter: PowerShell |
| Command & Control | T1071.001 Application Layer Protocol: Web Protocols, T1090 Proxy, T1573 Encrypted Channel |
Event coverage
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 1 | Process creation |
| Security-Auditing | Event ID 4688 | A new process has been created. |
Rule body yaml
title: Kalambur Backdoor Curl TOR SOCKS Proxy Execution
id: e99375eb-3ee0-407a-9f90-79569cc6a01c
status: experimental
description: Detects the execution of the "curl.exe" command, referencing "SOCKS" and ".onion" domains, which could be indicative of Kalambur backdoor activity.
references:
- https://blog.eclecticiq.com/sandworm-apt-targets-ukrainian-users-with-trojanized-microsoft-kms-activation-tools-in-cyber-espionage-campaigns
author: Arda Buyukkaya (EclecticIQ)
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
Stages and Predicates
Stage 0: condition
all of selection_*Stage 1: selection_img
selection_img:
Image|endswith: '\curl.exe'
Stage 2: selection_socks
selection_socks:
CommandLine|contains:
- 'socks5h://'
- 'socks5://'
- 'socks4a://'
Stage 3: selection_onion
selection_onion:
CommandLine|contains: '.onion'
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
CommandLine | match |
|
Image | ends_with |
|