Detection: Windows AD Short Lived Domain Controller SPN Attribute

Updated Date: 2024-05-11 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.

Search

 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 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| stats min(_time) as _time, values(ObjectDN) as ObjectDN values(OperationType) as OperationType by TargetLogonId src_user dest 
10| `windows_ad_short_lived_domain_controller_spn_attribute_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
Windows Event Log Security 4624	Windows	`'xmlwineventlog'`	`'XmlWinEventLog:Security'`	N/A

Macros Used

Name	Value
wineventlog_security	`eventtype=wineventlog_security OR Channel=security OR source=XmlWinEventLog: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

KillChainPhase.EXPLOITAITON

NistCategory.DE_CM

Cis18Value.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

Sneaky Active Directory Persistence Tricks

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
Short Lived Domain Controller SPN AD Attribute Triggered by $src_user$	100	100	100

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: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: 4