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Description

This search looks for PowerShell processes launched with arguments that have characters indicative of obfuscation on the command-line.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2021-01-19
  • Author: David Dorsey, Splunk
  • ID: cde75cf6-3c7a-4dd6-af01-27cdb4511fd4

ATT&CK

ID Technique Tactic
T1059 Command and Scripting Interpreter Execution
T1059.001 PowerShell Execution

| tstats `security_content_summariesonly` count values(Processes.process) as process values(Processes.parent_process) as parent_process min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where `process_powershell` by Processes.user Processes.process_name Processes.original_file_name Processes.parent_process_name Processes.dest Processes.process 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| eval num_obfuscation = (mvcount(split(process,"`"))-1) + (mvcount(split(process, "^"))-1) + (mvcount(split(process, "'"))-1) 
| `malicious_powershell_process_with_obfuscation_techniques_filter` 
| search num_obfuscation > 10 

Associated Analytic Story

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.

Required field

  • _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

Kill Chain Phase

  • Command and Control
  • Actions on Objectives

Known False Positives

These characters might be legitimately on the command-line, but it is not common.

RBA

Risk Score Impact Confidence Message
42.0 70 60 Powershell.exe running with potential obfuscated arguments on $dest$

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