LoFP / legitimate developers using microsoft devtunnels for testing and debugging may trigger this detection. filter alerts for approved development environments and personnel.

Techniques

• T1090

Sample rules

Windows Devtunnels Image Loaded

• source: splunk
• technicques:
  • T1090

Description

Detects image load events associated with Microsoft Devtunnels usage. Microsoft Devtunnels is a feature within Visual Studio that allows developers to expose their local development environment to the internet via secure, temporary tunnels, enabling external access for testing webhooks, APIs, and other services. While designed for legitimate development purposes, an attacker could exploit this feature to expose a compromised system or service to the internet, creating a covert communication channel that bypasses network security measures. By using Dev Tunnels, the attacker can establish a remote connection to the compromised environment, facilitate data exfiltration, or maintain command-and-control communications while avoiding detection by blending their activities with legitimate development traffic.

Detection logic

`sysmon`
EventID=7
ImageLoaded="*\\AppData\\Local\\Temp\\.net\\devtunnel\\*"
ImageLoaded="*devtunnel.dll"

| fillnull

| stats count min(_time) as firstTime
              max(_time) as lastTime
  by Computer ImageLoaded EventID loaded_file loaded_file_path process_exec process_guid
     process_hash process_id process_name process_path service_dll_signature_exists
     service_dll_signature_verified signature_id user_id vendor_product


| rename Computer as dest

| `security_content_ctime(firstTime)`

| `security_content_ctime(lastTime)`

| `windows_devtunnels_image_loaded_filter`