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Description

The following analytic utilizes PowerShell Script Block Logging (EventCode=4104) to identify the use of PowerShell environment variables to identify the current logged user. Red Teams and adversaries may leverage this method to identify the logged user on a compromised endpoint for situational awareness and Active Directory Discovery.

  • Type: Hunting
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2021-09-13
  • Author: Mauricio Velazco, Splunk
  • ID: 77f41d9e-b8be-47e3-ab35-5776f5ec1d20

ATT&CK

ID Technique Tactic
T1033 System Owner/User Discovery Discovery
`powershell` EventCode=4104 (Message = "*$env:UserName*" OR Message = "*[System.Environment]::UserName*") 
| stats count min(_time) as firstTime max(_time) as lastTime by EventCode Message ComputerName User 
| `security_content_ctime(firstTime)` 
| `user_discovery_with_env_vars_powershell_script_block_filter`

Associated Analytic Story

How To Implement

To successfully implement this analytic, you will need to enable PowerShell Script Block Logging on some or all endpoints. Additional setup here https://docs.splunk.com/Documentation/UBA/5.0.4.1/GetDataIn/AddPowerShell#Configure_module_logging_for_PowerShell.

Required field

  • _time
  • Path
  • Message
  • OpCode
  • ComputerName
  • User
  • EventCode

Kill Chain Phase

  • Reconnaissance

Known False Positives

Administrators or power users may use this PowerShell commandlet for troubleshooting.

RBA

Risk Score Impact Confidence Message
15.0 30 50 System user discovery 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

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