Detection: Windows PowerView SPN Discovery

Updated Date: 2024-05-13 ID: a7093c28-796c-4ebb-9997-e2c18b870837 Author: Gowthamaraj Rajendran, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the execution of the Get-DomainUser or Get-NetUser PowerShell cmdlets with the -SPN parameter, indicating the use of PowerView for SPN discovery. It leverages PowerShell Script Block Logging (EventCode=4104) to identify these specific commands. This activity is significant as it suggests an attempt to enumerate domain accounts associated with Service Principal Names (SPNs), a common precursor to Kerberoasting attacks. If confirmed malicious, this could allow an attacker to identify and target accounts for credential theft, potentially leading to unauthorized access and privilege escalation within the network.

1`powershell` EventCode=4104 (ScriptBlockText =*Get-NetUser* OR ScriptBlockText=*Get-DomainUser*) ScriptBlockText= *-SPN* 
2| stats count min(_time) as firstTime max(_time) as lastTime by EventCode ScriptBlockText Computer UserID 
3| rename Computer as dest 
4| rename UserID as user 
5| `security_content_ctime(firstTime)` 
6| `security_content_ctime(lastTime)`
7| `windows_powerview_spn_discovery_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_powerview_spn_discovery_filter search *
windows_powerview_spn_discovery_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
T1558 Steal or Forge Kerberos Tickets Credential Access
T1558.003 Kerberoasting Credential Access
KillChainPhase.EXPLOITAITON
NistCategory.DE_CM
Cis18Value.CIS_10
FIN7
Wizard Spider

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 Notable Yes
Rule Title %name%
Rule Description %description%
Notable Event Fields user, dest
Creates Risk Event True
This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

The following analytic requires PowerShell operational logs to be imported. Modify the powershell macro as needed to match the sourcetype or add index. This analytic is specific to 4104, or PowerShell Script Block Logging.

Known False Positives

False positive may include Administrators using PowerView for troubleshooting and management.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message Risk Score Impact Confidence
PowerView commandlets used for SPN discovery executed on $dest$ 27 30 90
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