Visual Studio Code Tunnel Shell Execution — Sigma Rule

Rule metadata and linked tags

Author: Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: medium. Source dates: 2023-10-25 / not supplied.

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

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 7b67ddab4a5e625eb28c151ae1de5d78a832e7f87fd77231e0a0cab6864f13af

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: Visual Studio Code Tunnel Shell Execution
id: f4a623c2-4ef5-4c33-b811-0642f702c9f1
status: test
description: Detects the execution of a shell (powershell, bash, wsl...) via Visual Studio Code tunnel. Attackers can abuse this functionality to establish a C2 channel and execute arbitrary commands on the system.
references:
    - https://ipfyx.fr/post/visual-studio-code-tunnel/
    - https://badoption.eu/blog/2023/01/31/code_c2.html
    - https://code.visualstudio.com/docs/remote/tunnels
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-10-25
tags:
    - attack.command-and-control
    - attack.t1071.001
logsource:
    category: process_creation
    product: windows
detection:
    selection_parent:
        ParentImage|contains: '\servers\Stable-'
        ParentImage|endswith: '\server\node.exe'
        ParentCommandLine|contains: '.vscode-server' # Technically one can host its own local server instead of using the VsCode one. And that would probably change the name (requires further research)
    # Note: Child processes (ie: shells) can be whatever technically (with some efforts)
    selection_child_1:
        Image|endswith:
            - '\powershell.exe'
            - '\pwsh.exe'
        CommandLine|contains: '\terminal\browser\media\shellIntegration.ps1'
    selection_child_2:
        Image|endswith:
            - '\wsl.exe'
            - '\bash.exe'
    condition: selection_parent and 1 of selection_child_*
falsepositives:
    - Legitimate use of Visual Studio Code tunnel and running code from there
level: medium

Original YAML and metadata in JSON

False positives

• Legitimate use of Visual Studio Code tunnel and running code from there

Source references

• https://ipfyx.fr/post/visual-studio-code-tunnel/
• https://badoption.eu/blog/2023/01/31/code_c2.html
• https://code.visualstudio.com/docs/remote/tunnels