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Description

The following analytic utilizes PowerShell Script Block Logging to identify the execution of the PowerView PowerShell commandlet Get-NetUser. In the context of PowerView's Get-NetUser cmdlet as a filter or parameter to query Active Directory user accounts that are not disabled. The full script block text based on the CISA-23-347A advisory is "Get-NetUser -UACFilter NOT_ACCOUNTDISABLE". Utilize this query to identify potential suspicious activity of user account enumeration.

  • Type: Hunting

  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

  • Last Updated: 2023-12-15
  • Author: Teoderick Contreras, Splunk
  • ID: eddbf5ba-b89e-47ca-995e-2d259804e55e

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1087 Account Discovery Discovery
T1087.001 Local Account Discovery
Kill Chain Phase
  • Exploitation
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


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`powershell` EventCode=4104  ScriptBlockText = "*Get-NetUser*" ScriptBlockText = "*NOT_ACCOUNTDISABLE*" ScriptBlockText = "*-UACFilter*" 
| rename Computer as dest, UserID as user 
| stats count min(_time) as firstTime max(_time) as lastTime by EventCode ScriptBlockText dest user 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_account_discovery_for_none_disable_user_account_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_account_discovery_for_none_disable_user_account_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • _time
  • ScriptBlockText
  • dest
  • EventCode
  • user

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 may leverage PowerView for legitimate purposes, filter as needed.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
15.0 30 50 Windows Account Discovery for None Disable User Account using PowerView's Get-NetUser on $dest$.

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

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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