Detection: Windows Account Discovery for None Disable User Account

Description

The following analytic detects the execution of the PowerView PowerShell cmdlet Get-NetUser with the UACFilter parameter set to NOT_ACCOUNTDISABLE, indicating an attempt to enumerate Active Directory user accounts that are not disabled. This detection leverages PowerShell Script Block Logging (EventCode 4104) to identify the specific script block text. Monitoring this activity is significant as it may indicate reconnaissance efforts by an attacker to identify active user accounts for further exploitation. If confirmed malicious, this activity could lead to unauthorized access, privilege escalation, or lateral movement within the network.

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

Data Source

Name Platform Sourcetype Source
Powershell Script Block Logging 4104 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Microsoft-Windows-PowerShell/Operational'

Macros Used

Name Value
powershell (source=WinEventLog:Microsoft-Windows-PowerShell/Operational OR source="XmlWinEventLog:Microsoft-Windows-PowerShell/Operational")
windows_account_discovery_for_none_disable_user_account_filter search *
windows_account_discovery_for_none_disable_user_account_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK
+ Kill Chain Phases
+ NIST
+ CIS
- Threat Actors
ID Technique Tactic
T1087 Account Discovery Discovery
T1087.001 Local Account Discovery
KillChainPhase.EXPLOITAITON
NistCategory.DE_AE
Cis18Value.CIS_10
Aquatic Panda
FIN13
APT1
APT3
APT32
APT41
Chimera
Fox Kitten
Ke3chang
Moses Staff
OilRig
Poseidon Group
RedCurl
Threat Group-3390
Turla
Volt Typhoon
admin@338

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
This configuration file applies to all detections of type hunting.

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 may leverage PowerView for legitimate purposes, filter as needed.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
Windows Account Discovery for None Disable User Account using PowerView's Get-NetUser on $dest$. 15 30 50
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

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: 4