Detection: Windows Devtunnels Execution

Description

Detects the execution of Microsoft devtunnels.exe. 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.

Search

 1
 2| tstats `security_content_summariesonly`
 3  count min(_time) as firstTime
 4        max(_time) as lastTime
 5
 6from datamodel=Endpoint.Processes where
 7
 8Processes.original_file_name="devtunnel.dll"
 9OR
10Processes.process_name="devtunnel.exe"
11
12by Processes.process Processes.vendor_product Processes.user_id Processes.process_hash
13   Processes.parent_process_name Processes.parent_process_exec Processes.action
14   Processes.dest Processes.process_current_directory Processes.process_path
15   Processes.process_integrity_level Processes.original_file_name Processes.parent_process
16   Processes.parent_process_path Processes.parent_process_guid Processes.parent_process_id
17   Processes.process_guid Processes.process_id Processes.user Processes.process_name
18
19
20| `drop_dm_object_name(Processes)`
21
22| `security_content_ctime(firstTime)`
23
24| `security_content_ctime(lastTime)`
25
26| `windows_devtunnels_execution_filter`

Data Source

Name	Platform	Sourcetype	Source
CrowdStrike ProcessRollup2	Other	'crowdstrike:events:sensor'	'crowdstrike'
Sysmon EventID 1	Windows	'XmlWinEventLog'	'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'
Windows Event Log Security 4688	Windows	'XmlWinEventLog'	'XmlWinEventLog:Security'

Macros Used

Annotations

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Implementation

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

Some legitimate developers may use Microsoft Devtunnels for testing and debugging their applications. Filter alerts for approved development environments and users.

Associated Analytic Story

• Reverse Network Proxy

Risk Based Analytics (RBA)

Risk Message:

Potential Devtunnels execution observed on $dest$ via $process$.

References

• https://blueteamops.medium.com/detecting-dev-tunnels-16f0994dc3e2

Detection Testing

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 1