PUA - 3Proxy Execution — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems). Source status: test; severity: high. Source dates: 2022-09-13 / 2023-02-21.

{
  "category": "process_creation",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 2f9742c3c49ff9f2e50e0c9dd82ec8dc64b8e5a8ae89d8371b4d8ed73160e20b

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: PUA - 3Proxy Execution
id: f38a82d2-fba3-4781-b549-525efbec8506
status: test
description: Detects the use of 3proxy, a tiny free proxy server
references:
    - https://github.com/3proxy/3proxy
    - https://blog.talosintelligence.com/2022/09/lazarus-three-rats.html
author: Florian Roth (Nextron Systems)
date: 2022-09-13
modified: 2023-02-21
tags:
    - attack.command-and-control
    - attack.t1572
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        Image|endswith: '\3proxy.exe'
    selection_pe:
        Description: '3proxy - tiny proxy server'
    selection_params: # param combos seen in the wild
        CommandLine|contains: '.exe -i127.0.0.1 -p'
    condition: 1 of selection_*
falsepositives:
    - Administrative activity
level: high

Original YAML and metadata in JSON

False positives

• Administrative activity

Source references

• https://github.com/3proxy/3proxy
• https://blog.talosintelligence.com/2022/09/lazarus-three-rats.html