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Description

This search looks for a process launching an *.lnk file under C:\User* or *\Local\Temp\*. This is common behavior used by various spear phishing tools.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2021-08-26
  • Author: Jose Hernandez, Splunk
  • ID: 5d814af1-1041-47b5-a9ac-d754e82e9a26

ATT&CK

ID Technique Tactic
T1566.002 Spearphishing Link Initial Access

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime FROM datamodel=Endpoint.Filesystem where Filesystem.file_name="*.lnk" AND (Filesystem.file_path="C:\\User\\*" OR Filesystem.file_path="*\\Temp\\*") by _time span=1h Filesystem.process_guid Filesystem.file_name Filesystem.file_path Filesystem.file_hash Filesystem.user 
| `drop_dm_object_name(Filesystem)` 
| rename process_guid as lnk_guid 
| join lnk_guid, _time [
| tstats `security_content_summariesonly` count FROM datamodel=Endpoint.Processes where Processes.process_name=* by _time span=1h Processes.parent_process_guid Processes.process_id Processes.process_name Processes.dest Processes.process_path Processes.process 
| `drop_dm_object_name(Processes)` 
| rename parent_process_guid as lnk_guid 
| fields _time lnk_guid process_id dest process_name process_path process] 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| table firstTime, lastTime, lnk_guid, process_id, user, dest, file_name, file_path, process_name, process, process_path, file_hash 
| `process_creating_lnk_file_in_suspicious_location_filter`

Associated Analytic Story

How To Implement

You must be ingesting data that records filesystem and process activity from your hosts to populate the Endpoint data model. This is typically populated via endpoint detection-and-response product, such as Carbon Black, or endpoint data sources, such as Sysmon.

Required field

  • _time
  • Filesystem.file_name
  • Filesystem.file_path
  • Filesystem.process_id
  • Filesystem.file_name
  • Filesystem.file_path
  • Filesystem.file_hash
  • Filesystem.user

Kill Chain Phase

  • Installation
  • Actions on Objectives

Known False Positives

This detection should yield little or no false positive results. It is uncommon for LNK files to be executed from temporary or user directories.

RBA

Risk Score Impact Confidence Message
63.0 70 90 A process $process_name$ that launching .lnk file in $file_path$ in host $dest$

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

source | version: 5