Detection: Windows Identify Protocol Handlers

Description

The following analytic identifies the use of protocol handlers executed via the command line. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process and command-line telemetry. This activity is significant because protocol handlers can be exploited to execute arbitrary commands or launch applications, potentially leading to unauthorized actions. If confirmed malicious, an attacker could use this technique to gain code execution, escalate privileges, or maintain persistence within the environment, posing a significant security risk.

Search

1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime values(Processes.process) as process values(Processes.parent_process) as parent_process from datamodel=Endpoint.Processes  by Processes.dest Processes.parent_process_name Processes.user Processes.process_name Processes.process 
3| `security_content_ctime(firstTime)` 
4| `security_content_ctime(lastTime)` 
5| `drop_dm_object_name(Processes)` 
6| lookup windows_protocol_handlers handler AS process OUTPUT handler ishandler 
7| where ishandler="TRUE" 
8| `windows_identify_protocol_handlers_filter`

Data Source

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

False positives will be found. https and http is a URL Protocol handler that will trigger this analytic. Tune based on process or command-line.

Associated Analytic Story

• Living Off The Land

Risk Based Analytics (RBA)

References

• https://gist.github.com/MHaggis/a0d3edb57d36e0916c94c0a464b2722e

• https://www.oreilly.com/library/view/learning-java/1565927184/apas02.html

• https://blogs.windows.com/msedgedev/2022/01/20/getting-started-url-protocol-handlers-microsoft-edge/

• https://github.com/Mr-Un1k0d3r/PoisonHandler

• https://www.mdsec.co.uk/2021/03/phishing-users-to-take-a-test/

• https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1218/T1218.md#atomic-test-5---protocolhandlerexe-downloaded-a-suspicious-file

• https://techcommunity.microsoft.com/t5/windows-it-pro-blog/disabling-the-msix-ms-appinstaller-protocol-handler/ba-p/3119479

• https://www.huntress.com/blog/microsoft-office-remote-code-execution-follina-msdt-bug

• https://parsiya.net/blog/2021-03-17-attack-surface-analysis-part-2-custom-protocol-handlers/

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: 4