ID | Technique | Tactic |
---|---|---|
T1033 | System Owner/User Discovery | Discovery |
Detection: GetCurrent User with PowerShell Script Block
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.
Search
1`powershell` EventCode=4104 ScriptBlockText = "*[System.Security.Principal.WindowsIdentity]*" ScriptBlockText = "*GetCurrent()*"
2| stats count min(_time) as firstTime max(_time) as lastTime by EventCode ScriptBlockText Computer UserID
3| rename Computer as dest, UserID as user
4| `security_content_ctime(firstTime)`
5| `security_content_ctime(lastTime)`
6| `getcurrent_user_with_powershell_script_block_filter`
Data Source
Name | Platform | Sourcetype | Source | Supported App |
---|---|---|---|---|
Powershell Script Block Logging 4104 | Windows | 'xmlwineventlog' |
'XmlWinEventLog:Microsoft-Windows-PowerShell/Operational' |
N/A |
Macros Used
Name | Value |
---|---|
powershell | (source=WinEventLog:Microsoft-Windows-PowerShell/Operational OR source="XmlWinEventLog:Microsoft-Windows-PowerShell/Operational") |
getcurrent_user_with_powershell_script_block_filter | search * |
getcurrent_user_with_powershell_script_block_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
Default Configuration
This detection is configured by default in Splunk Enterprise Security to run with the following settings:
Setting | Value |
---|---|
Disabled | true |
Cron Schedule | 0 * * * * |
Earliest Time | -70m@m |
Latest Time | -10m@m |
Schedule Window | auto |
Creates Risk Event | False |
Implementation
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.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
System user discovery on $dest$ by $user$ | 15 | 30 | 50 |
References
Detection Testing
Test Type | Status | Dataset | Source | Sourcetype |
---|---|---|---|---|
Validation | ✅ Passing | N/A | N/A | N/A |
Unit | ✅ Passing | Dataset | XmlWinEventLog:Microsoft-Windows-PowerShell/Operational |
xmlwineventlog |
Integration | ✅ Passing | Dataset | XmlWinEventLog:Microsoft-Windows-PowerShell/Operational |
xmlwineventlog |
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: GitHub | Version: 3