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Description

This search looks for changes to registry values that control Windows file associations, executed by a process that is not typical for legitimate, routine changes to this area.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2020-07-22
  • Author: Rico Valdez, Splunk
  • ID: 1b989a0e-0129-4446-a695-f193a5b746fc

Annotations

ATT&CK
ID Technique Tactic
T1546.001 Change Default File Association Persistence, Privilege Escalation
Kill Chain Phase
  • Actions on Objectives
NIST
  • DE.CM
  • PR.PT
  • PR.IP
CIS20
  • CIS 3
  • CIS 8
CVE
1
2
3
4
5
6
7
8
9
10
| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime values(Processes.process_name) as process_name values(Processes.parent_process_name) as parent_process_name FROM datamodel=Endpoint.Processes where Processes.process_name!=Explorer.exe AND Processes.process_name!=OpenWith.exe by Processes.process_id Processes.dest 
| `drop_dm_object_name("Processes")` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| join [
| tstats `security_content_summariesonly` values(Registry.registry_path) as registry_path count from datamodel=Endpoint.Registry where Registry.registry_path=*\\Explorer\\FileExts* by Registry.process_id Registry.dest 
| `drop_dm_object_name("Registry")` 
| table process_id dest registry_path]
| `suspicious_changes_to_file_associations_filter` 

Macros

The SPL above uses the following Macros:

Note that suspicious_changes_to_file_associations_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required field

  • _time

How To Implement

To successfully implement this search you need to be ingesting information on registry changes that include the name of the process responsible for the changes from your endpoints into the Endpoint datamodel in the Processes and Registry nodes.

Known False Positives

There may be other processes in your environment that users may legitimately use to modify file associations. If this is the case and you are finding false positives, you can modify the search to add those processes as exceptions.

Associated Analytic story

RBA

Risk Score Impact Confidence Message
25.0 50 50 tbd

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

source | version: 4