DNS Query To Devtunnels Domain — Sigma Rule

Rule metadata and linked tags

Author: citron_ninja. Source status: test; severity: medium. Source dates: 2023-10-25 / 2023-11-20.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 9310b4ba27cf79154f552099612db091d68ca08c65ae689d92ef22add279fed2

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: DNS Query To Devtunnels Domain
id: 1cb0c6ce-3d00-44fc-ab9c-6d6d577bf20b
related:
    - id: 9501f8e6-8e3d-48fc-a8a6-1089dd5d7ef4 # Net Connection DevTunnels
      type: similar
    - id: 4b657234-038e-4ad5-997c-4be42340bce4 # Net Connection VsCode
      type: similar
    - id: b3e6418f-7c7a-4fad-993a-93b65027a9f1 # DNS VsCode
      type: similar
status: test
description: |
    Detects DNS query requests to Devtunnels domains. Attackers can abuse that feature to establish a reverse shell or persistence on a machine.
references:
    - https://blueteamops.medium.com/detecting-dev-tunnels-16f0994dc3e2
    - https://learn.microsoft.com/en-us/azure/developer/dev-tunnels/security
    - https://cydefops.com/devtunnels-unleashed
author: citron_ninja
date: 2023-10-25
modified: 2023-11-20
tags:
    - attack.command-and-control
    - attack.t1071.001
    - attack.t1572
logsource:
    category: dns_query
    product: windows
detection:
    selection:
        QueryName|endswith: '.devtunnels.ms'
    condition: selection
falsepositives:
    - Legitimate use of Devtunnels will also trigger this.
level: medium

Original YAML and metadata in JSON

False positives

• Legitimate use of Devtunnels will also trigger this.

Source references

• https://blueteamops.medium.com/detecting-dev-tunnels-16f0994dc3e2
• https://learn.microsoft.com/en-us/azure/developer/dev-tunnels/security
• https://cydefops.com/devtunnels-unleashed