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.

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Detection logic

selection_img

Image|endswith: \curl.exe

selection_socks

CommandLine|contains:
  - socks5h://
  - socks5://
  - socks4a://

selection_onion

CommandLine|contains: .onion

Condition

all of selection_*

Raw 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