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Description

This analytic is developed to detect suspicious registry modification to change the default file association of windows to malicious payload. This techninique was seen in some APT where it modify the default process to run file association, like .txt to notepad.exe. Instead notepad.exe it will point to a Script or other payload that will load malicious command to the compromised host.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2021-09-27
  • Author: Teoderick Contreras, Splunk
  • ID: 462d17d8-1f71-11ec-ad07-acde48001122

ATT&CK

ID Technique Tactic
T1546.001 Change Default File Association Privilege Escalation, Persistence
T1546 Event Triggered Execution Privilege Escalation, Persistence

| tstats `security_content_summariesonly` count  min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Registry where Registry.registry_path ="*\\shell\\open\\command\\*" Registry.registry_path = "*HKCR\\*" by Registry.dest  Registry.user Registry.registry_path Registry.registry_key_name Registry.registry_value_name 
| `security_content_ctime(lastTime)` 
| `security_content_ctime(firstTime)` 
| `drop_dm_object_name(Registry)` 
| `change_default_file_association_filter`

Associated Analytic Story

How To Implement

To successfully implement this search, you must be ingesting data that records registry activity from your hosts to populate the endpoint data model in the registry node. This is typically populated via endpoint detection-and-response product, such as Carbon Black or endpoint data sources, such as Sysmon. The data used for this search is typically generated via logs that report reads and writes to the registry.

Required field

  • _time
  • Registry.dest
  • Registry.user
  • Registry.registry_path
  • Registry.registry_key_name
  • Registry.registry_value_name

Kill Chain Phase

  • Exploitation

Known False Positives

unknown

RBA

Risk Score Impact Confidence Message
80.0 80 100 modified/added/deleted registry entry $Registry.registry_path$ in $dest$

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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