GetCurrent User with PowerShell Script Block

 Original Source: [splunk source]
Name:GetCurrent User with PowerShell Script Block
id:80879283-c30f-44f7-8471-d1381f6d437a
version:10
date:None
author:Mauricio Velazco, Splunk
status:production
type:Hunting
Description:The following analytic detects the execution of the `GetCurrent` method from the WindowsIdentity .NET class using PowerShell Script Block Logging (EventCode=4104). This method identifies the current Windows user. The detection leverages PowerShell script block logs to identify when this method is called. This activity is significant because adversaries and Red Teams may use it to gain situational awareness and perform Active Directory discovery on compromised endpoints. If confirmed malicious, this could allow attackers to map out user accounts and potentially escalate privileges or move laterally within the network.
Data_source:
  • -Powershell Script Block Logging 4104
search:`powershell` EventCode=4104 ScriptBlockText = "*[System.Security.Principal.WindowsIdentity]*" ScriptBlockText = "*GetCurrent()*"

| fillnull

| stats count min(_time) as firstTime max(_time) as lastTime
BY dest signature signature_id
user_id vendor_product EventID
Guid Opcode Name
Path ProcessID ScriptBlockId
ScriptBlockText

| `security_content_ctime(firstTime)`

| `security_content_ctime(lastTime)`

| `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://help.splunk.com/en/security-offerings/splunk-user-behavior-analytics/get-data-in/5.4.1/add-other-data-to-splunk-uba/configure-powershell-logging-to-see-powershell-anomalies-in-splunk-uba.
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-6.0&viewFallbackFrom=net-5.0
drilldown_searches:
  :
analytic_story:['Active Directory Discovery']

asset_type:Endpoint

mitre_attack_id:['T1033']

product:['Splunk Enterprise', 'Splunk Enterprise Security', 'Splunk Cloud']

category:endpoint

security_domain:endpoint

tags:

tests:
 name:'True Positive Test'
 attack_data:
  data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1033/AD_discovery/windows-powershell-xml.log
  source: XmlWinEventLog:Microsoft-Windows-PowerShell/Operational
  sourcetype: XmlWinEventLog
 test_type:'unit'
manual_test:None

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