Detection: Windows Domain Account Discovery Via Get-NetComputer

Updated Date: 2024-05-30 ID: a7fbbc4e-4571-424a-b627-6968e1c939e4 Author: Teoderick Contreras, Splunk Type: Anomaly Product: Splunk Enterprise Security

Description

The following analytic detects the execution of the PowerView PowerShell cmdlet Get-NetComputer, which is used to query Active Directory for user account details such as "samaccountname," "accountexpires," "lastlogon," and more. 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, which is often a precursor to further malicious actions. If confirmed malicious, this activity could lead to unauthorized access, privilege escalation, or lateral movement within the network.

1`powershell` EventCode=4104  ScriptBlockText = "*Get-NetComputer*" ScriptBlockText IN ("*samaccountname*", "*accountexpires*", "*lastlogon*", "*lastlogoff*", "*pwdlastset*", "*logoncount*") 
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_domain_account_discovery_via_get_netcomputer_filter`

Data Source

Name Platform Sourcetype Source Supported App
Powershell Script Block Logging 4104 Windows icon 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")
windows_domain_account_discovery_via_get_netcomputer_filter search *
windows_domain_account_discovery_via_get_netcomputer_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
T1087.002 Domain Account Discovery
KillChainPhase.EXPLOITAITON
NistCategory.DE_AE
Cis18Value.CIS_10
FIN13
APT41
BRONZE BUTLER
Chimera
Dragonfly
FIN13
FIN6
Fox Kitten
Ke3chang
LAPSUS$
MuddyWater
OilRig
Poseidon Group
Sandworm Team
Scattered Spider
ToddyCat
Turla
Volt Typhoon
Wizard Spider
menuPass

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 Risk Score Impact Confidence
Windows Domain Account Discovery Via Get-NetComputer in $dest$. 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: 2