name: GetCurrent User with PowerShell Script Block
id: 80879283-c30f-44f7-8471-d1381f6d437a
version: 1
date: '2021-09-13'
author: Mauricio Velazco, Splunk
type: Hunting
datamodel:
- Endpoint
description: The following analytic utilizes PowerShell Script Block Logging (EventCode=4104)
  to identify the execution of the `GetCurrent` method of the WindowsIdentity .NET
  class. This method returns an object that represents the current Windows 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.
search: '`powershell` EventCode=4104 (Message = "*[System.Security.Principal.WindowsIdentity]*"
  AND Message = "*GetCurrent()*") | stats count min(_time) as firstTime max(_time)
  as lastTime by EventCode Message ComputerName User | `security_content_ctime(firstTime)`
  | `getcurrent_user_with_powershell_script_block_filter`'
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.
known_false_positives: Administrators or power users may use this PowerShell commandlet
  for troubleshooting.
references:
- https://attack.mitre.org/techniques/T1033/
- https://docs.microsoft.com/en-us/dotnet/api/system.security.principal.windowsidentity.getcurrent?view=net-5.0
tags:
  analytic_story:
  - Active Directory Discovery
  dataset:
  - https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1033/AD_discovery/windows-powershell.log
  kill_chain_phases:
  - Reconnaissance
  mitre_attack_id:
  - T1033
  product:
  - Splunk Enterprise
  - Splunk Enterprise Security
  - Splunk Cloud
  required_fields:
  - _time
  - Path 
  - Message
  - OpCode 
  - ComputerName 
  - User
  - EventCode
  security_domain: endpoint
  impact: 30
  confidence: 50
  risk_score: 15
  context:
  - Source:Endpoint
  - Stage:Discovery
  - Stage:Recon
  message: System user discovery on $dest$
  observable:
  - name: dest
    type: Endpoint
    role:
    - Victim
  automated_detection_testing: passed