Network Connection Initiated To Visual Studio Code Tunnels Domain

Status: test
Severity: medium
Log source: category network_connection, product windows
Author: Kamran Saifullah
Source: github.com/SigmaHQ/sigma

Detects network connections to Visual Studio Code tunnel domains initiated by a process on a system. Attackers can abuse that feature to establish a reverse shell or persistence on a machine.

Known false positives

Legitimate use of Visual Studio Code tunnel will also trigger this.

MITRE ATT&CK coverage

Tactic	Techniques
Command & Control	`T1572` Protocol Tunneling
Exfiltration	`T1567` Exfiltration Over Web Service

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 3: Network connection

Rule body

title: Network Connection Initiated To Visual Studio Code Tunnels Domain
id: 4b657234-038e-4ad5-997c-4be42340bce4
related:
    - id: 9501f8e6-8e3d-48fc-a8a6-1089dd5d7ef4 # Net Connection DevTunnels
      type: similar
    - id: b3e6418f-7c7a-4fad-993a-93b65027a9f1 # DNS VsCode
      type: similar
    - id: 1cb0c6ce-3d00-44fc-ab9c-6d6d577bf20b # DNS DevTunnels
      type: similar
status: test
description: |
    Detects network connections to Visual Studio Code tunnel domains initiated by a process on a system. Attackers can abuse that feature to establish a reverse shell or persistence on a machine.
references:
    - https://ipfyx.fr/post/visual-studio-code-tunnel/
    - https://badoption.eu/blog/2023/01/31/code_c2.html
    - https://cydefops.com/vscode-data-exfiltration
author: Kamran Saifullah
date: 2023-11-20
tags:
    - attack.exfiltration
    - attack.command-and-control
    - attack.t1567
    - attack.t1572
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        Initiated: 'true'
        DestinationHostname|endswith: '.tunnels.api.visualstudio.com'
    condition: selection
falsepositives:
    - Legitimate use of Visual Studio Code tunnel will also trigger this.
level: medium

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    Initiated: 'true'
    DestinationHostname|endswith: '.tunnels.api.visualstudio.com'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`DestinationHostname`	ends_with	`.tunnels.api.visualstudio.com`	`field:"DestinationHostname" kind:ends_with value:".tunnels.api.visualstudio.com"`
`Initiated`	eq	`true` corpus 50 (sigma 50)	`field:"Initiated" kind:eq value:"true"`