Detection: Windows AD ServicePrincipalName Added To Domain Account

Updated Date: 2024-10-16 ID: 8a1259cb-0ea7-409c-8bfe-74bad89259f9 Author: Mauricio Velazco, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the addition of a Service Principal Name (SPN) to a domain account. It leverages Windows Event Code 5136 and monitors changes to the servicePrincipalName attribute. This activity is significant because it may indicate an attempt to perform Kerberoasting, a technique where attackers extract and crack service account passwords offline. If confirmed malicious, this could allow an attacker to obtain cleartext passwords, leading to unauthorized access and potential lateral movement within the domain environment.

Search

1`wineventlog_security` EventCode=5136 AttributeLDAPDisplayName=servicePrincipalName OperationType="%%14674" ObjectClass=user 
2| stats values(ObjectDN) as ObjectDN by _time, Computer, SubjectUserName, AttributeValue 
3| rex field=ObjectDN "^CN=(?P<user>[a-zA-Z0-9!#$%&'@^_{}~.-]+)," 
4| rename Computer as dest, SubjectUserName as src_user  
5| `windows_ad_serviceprincipalname_added_to_domain_account_filter`

Data Source

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

Macros Used

Name	Value
wineventlog_security	`eventtype=wineventlog_security OR Channel=security OR source=XmlWinEventLog:Security`
windows_ad_serviceprincipalname_added_to_domain_account_filter	`search *`

windows_ad_serviceprincipalname_added_to_domain_account_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
T1098	Account Manipulation	Persistence

KillChainPhase.EXPLOITAITON

KillChainPhase.INSTALLATION

NistCategory.DE_CM

Cis18Value.CIS_10

HAFNIUM

Lazarus Group

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 ned to be ingesting eventcode 5136. The Advanced Security Audit policy setting Audit Directory Services Changes within DS Access needs to be enabled. Additionally, a SACL needs to be created for AD objects in order to ingest attribute modifications.

Known False Positives

A Service Principal Name should only be added to an account when an application requires it. While infrequent, this detection may trigger on legitimate actions. Filter as needed.

Associated Analytic Story

Sneaky Active Directory Persistence Tricks

Risk Based Analytics (RBA)

Risk Message	Risk Score	Impact	Confidence
A Servince Principal Name for $ObjectDN$ was set by $user$	30	60	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: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: 5