Cloudflared Tunnels Related DNS Requests — Sigma Rule

Rule metadata and linked tags

Author: Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: medium. Source dates: 2023-12-20 / not supplied.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: fd13410291e35e7ed43ec6cdd069e7dd28321f40cdc0dd8386eb05548f3db53e

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: Cloudflared Tunnels Related DNS Requests
id: a1d9eec5-33b2-4177-8d24-27fe754d0812
related:
    - id: 7cd1dcdc-6edf-4896-86dc-d1f19ad64903
      type: similar
status: test
description: |
    Detects DNS requests to Cloudflared tunnels domains.
    Attackers can abuse that feature to establish a reverse shell or persistence on a machine.
references:
    - https://www.guidepointsecurity.com/blog/tunnel-vision-cloudflared-abused-in-the-wild/
    - Internal Research
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-12-20
tags:
    - attack.command-and-control
    - attack.t1071.001
    - attack.t1572
logsource:
    category: dns_query
    product: windows
detection:
    selection:
        QueryName|endswith:
            - '.v2.argotunnel.com'
            - 'protocol-v2.argotunnel.com'
            - 'trycloudflare.com'
            - 'update.argotunnel.com'
    condition: selection
falsepositives:
    - Legitimate use of cloudflare tunnels will also trigger this.
level: medium

Original YAML and metadata in JSON

False positives

• Legitimate use of cloudflare tunnels will also trigger this.

Source references

• https://www.guidepointsecurity.com/blog/tunnel-vision-cloudflared-abused-in-the-wild/
• Internal Research (source note; no public URL supplied)