Detection: Windows Account Discovery for Sam Account Name

Updated Date: 2024-11-13 ID: 69934363-e1dd-4c49-8651-9d7663dd4d2f Author: Teoderick Contreras, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

The following analytic detects the execution of the PowerView PowerShell cmdlet Get-NetUser, specifically querying for "samaccountname" and "pwdlastset" attributes. It leverages Event ID 4104 from PowerShell Script Block Logging to identify this activity. This behavior is significant as it may indicate an attempt to gather user account information from Active Directory, which is a common reconnaissance step in lateral movement or privilege escalation attacks. If confirmed malicious, this activity could allow an attacker to map out user accounts, potentially leading to further exploitation and unauthorized access within the network.

1`powershell` EventCode=4104  ScriptBlockText = "*Get-NetUser*" ScriptBlockText IN ("*samaccountname*", "*pwdlastset*") 
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_sam_account_name_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_sam_account_name_filter search *
windows_account_discovery_for_sam_account_name_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
Exploitation
DE.AE
CIS 10
Aquatic Panda
FIN13

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 True
This configuration file applies to all detections of type anomaly. These detections will use Risk Based Alerting.

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:

Windows Account Discovery for Sam Account Name on $dest$.

Risk Object Risk Object Type Risk Score Threat Objects
dest system 15 No Threat Objects

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