Communication To Ngrok Tunneling Service - Linux — Sigma Rule

Rule metadata and linked tags

Author: Florian Roth (Nextron Systems). Source status: test; severity: high. Source dates: 2022-11-03 / not supplied.

{
  "product": "linux",
  "category": "network_connection"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: c3466742b9092eed5b8296d6fe4bdf77fa287ca8cc6ef394f833ba170e388015

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: Communication To Ngrok Tunneling Service - Linux
id: 19bf6fdb-7721-4f3d-867f-53467f6a5db6
status: test
description: Detects an executable accessing an ngrok tunneling endpoint, which could be a sign of forbidden exfiltration of data exfiltration by malicious actors
references:
    - https://twitter.com/hakluke/status/1587733971814977537/photo/1
    - https://ngrok.com/docs/secure-tunnels/tunnels/ssh-reverse-tunnel-agent
author: Florian Roth (Nextron Systems)
date: 2022-11-03
tags:
    - attack.exfiltration
    - attack.command-and-control
    - attack.t1567
    - attack.t1568.002
    - attack.t1572
    - attack.t1090
    - attack.t1102
    - attack.s0508
logsource:
    product: linux
    category: network_connection
detection:
    selection:
        DestinationHostname|contains:
            - 'tunnel.us.ngrok.com'
            - 'tunnel.eu.ngrok.com'
            - 'tunnel.ap.ngrok.com'
            - 'tunnel.au.ngrok.com'
            - 'tunnel.sa.ngrok.com'
            - 'tunnel.jp.ngrok.com'
            - 'tunnel.in.ngrok.com'
    condition: selection
falsepositives:
    - Legitimate use of ngrok
level: high

Original YAML and metadata in JSON

False positives

• Legitimate use of ngrok

Source references

• https://twitter.com/hakluke/status/1587733971814977537/photo/1
• https://ngrok.com/docs/secure-tunnels/tunnels/ssh-reverse-tunnel-agent