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Description

The following hunting analytic will identify any protocol handlers utilized on the command-line. A protocol handler is an application that knows how to handle particular types of links: for example, a mail client is a protocol handler for "mailto:" links. When the user clicks a "mailto:" link, the browser opens the application selected as the handler for the "mailto:" protocol (or offers them a choice of handlers, depending on their settings). To identify protocol handlers we can use NirSoft https://www.nirsoft.net/utils/url_protocol_view.html URLProtocolView or query the registry using PowerShell: get-Item Registry::HKEY_CLASSES_ROOT* Select-Object "Property","PSChildName" Where-Object -Property Property -Match "^URL*" # Export-Csv -path c:\temp\url_all.csv. Note my query is limited to URL in the property to limit the scope of this query to similar handlers as ms-msdt.
  • Type: Hunting
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2022-07-11
  • Author: Michael Haag, Splunk
  • ID: bd5c311e-a6ea-48ae-a289-19a3398e3648

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1059 Command and Scripting Interpreter Execution
Kill Chain Phase
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 3
  • CIS 5
  • CIS 16
CVE
1
2
3
4
5
6
7
8
| 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.user Processes.process_name Processes.process 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `drop_dm_object_name(Processes)` 
| lookup windows_protocol_handlers handler AS process OUTPUT handler ishandler 
| where ishandler="TRUE" 
| `windows_identify_protocol_handlers_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_identify_protocol_handlers_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Lookups

The SPL above uses the following Lookups:

Required fields

List of fields required to use this analytic.

  • _time
  • Processes.dest
  • Processes.user
  • Processes.parent_process_name
  • Processes.parent_process
  • Processes.original_file_name
  • Processes.process_name
  • Processes.process
  • Processes.process_id
  • Processes.parent_process_path
  • Processes.process_path
  • Processes.parent_process_id

How To Implement

To successfully implement this search you need to be ingesting information on process that include the name of the process responsible for the changes from your endpoints into the Endpoint datamodel in the Processes node. In addition, confirm the latest CIM App 4.20 or higher is installed and the latest TA for the endpoint product.

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

RBA

Risk Score Impact Confidence Message
6.0 30 20 An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$ utilizing a protocol handler.

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

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

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