Detection: Windows AD Short Lived Domain Controller SPN Attribute

Updated Date: 2024-12-10 ID: 57e27f27-369c-4df8-af08-e8c7ee8373d4 Author: Dean Luxton Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the temporary addition of a global catalog SPN or a DRS RPC SPN to an Active Directory computer object, indicative of a potential DCShadow attack. This detection leverages EventCode 5136 from the wineventlog_security data source, focusing on specific SPN attribute changes. This activity is significant as DCShadow attacks allow attackers with privileged access to register rogue Domain Controllers, enabling unauthorized changes to the AD infrastructure. If confirmed malicious, this could lead to unauthorized replication of changes, including credentials and keys, compromising the entire domain's security.

1`wineventlog_security` EventCode=5136 AttributeLDAPDisplayName=servicePrincipalName (AttributeValue="GC/*" OR AttributeValue="E3514235-4B06-11D1-AB04-00C04FC2DCD2/*") 
2| stats min(_time) as _time range(_time) as duration values(OperationType) as OperationType values(user) as user values(src_ip) as src_ip values(src_nt_domain) as src_nt_domain values(src_user) as src_user values(Computer) as dest, values(ObjectDN) as ObjectDN values(action) as action values(app) as app values(authentication_method) as authentication_method values(signature) as signature values(signature_id) as signature_id values(src) as src by Logon_ID 
3| eval short_lived=case((duration<30),"TRUE") 
4| where short_lived="TRUE" AND mvcount(OperationType)>1 
5| replace "%%14674" with "Value Added", "%%14675" with "Value Deleted" in OperationType 
6| rename Logon_ID as TargetLogonId 
7| appendpipe [
8| map search="search `wineventlog_security` EventCode=4624 TargetLogonId=$TargetLogonId$"] 
9| `windows_ad_short_lived_domain_controller_spn_attribute_filter`

Data Source

Name Platform Sourcetype Source
Windows Event Log Security 4624 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Security'
Windows Event Log Security 5136 Windows icon Windows 'xmlwineventlog' 'XmlWinEventLog:Security'

Macros Used

Name Value
wineventlog_security eventtype="wineventlog_security" OR Channel="security" OR source="XmlWinEventLog:Security" OR source="WinEventLog:Security"
windows_ad_short_lived_domain_controller_spn_attribute_filter search *
windows_ad_short_lived_domain_controller_spn_attribute_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
T1207 Rogue Domain Controller Defense Evasion
Exploitation
DE.CM
CIS 10

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

To successfully implement this search, you need to be ingesting eventcode 5136. The Advanced Security Audit policy setting Audit Directory Services Changes within DS Access needs to be enabled, alongside a SACL for everybody to Write All Properties applied to the domain root and all descendant objects.

Known False Positives

None.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message:

Short Lived Domain Controller SPN AD Attribute Triggered by $src_user$

Risk Object Risk Object Type Risk Score Threat Objects
src_user user 100 No Threat Objects

References

Detection Testing

Test Type Status Dataset Source Sourcetype
Validation ✅ Passing N/A N/A N/A
Unit ✅ Passing Dataset XmlWinEventLog:Security XmlWinEventLog
Integration ✅ Passing Dataset XmlWinEventLog:Security 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: 8