Detection: Windows AD Short Lived Domain Account ServicePrincipalName

Updated Date: 2024-05-18 ID: b681977c-d90c-4efc-81a5-c58f945fb541 Author: Mauricio Velazco, Splunk Type: TTP Product: Splunk Enterprise Security

Description

The following analytic identifies the addition and quick deletion of a Service Principal Name (SPN) to a domain account within 5 minutes. This detection leverages EventCode 5136 from the Windows Security Event Log, focusing on changes to the servicePrincipalName attribute. This activity is significant as it may indicate an attempt to perform Kerberoasting, a technique used to crack the cleartext password of a domain account offline. If confirmed malicious, this could allow an attacker to gain unauthorized access to sensitive information or escalate privileges within the domain environment.

Search

1 `wineventlog_security` EventCode=5136 AttributeLDAPDisplayName=servicePrincipalName 
2| transaction ObjectDN AttributeValue startswith=(EventCode=5136 OperationType="%%14674") endswith=(EventCode=5136 OperationType="%%14675") 
3| eval short_lived=case((duration<300),"TRUE") 
4| search short_lived = TRUE 
5| rename ObjectDN as user 
6| `windows_ad_short_lived_domain_account_serviceprincipalname_filter`

Data Source

Name	Platform	Sourcetype	Source	Supported App
Windows Event Log Security 5136	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_account_serviceprincipalname_filter	`search *`

windows_ad_short_lived_domain_account_serviceprincipalname_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

APT3

APT41

APT5

Dragonfly

FIN13

HAFNIUM

Kimsuky

Lazarus Group

Magic Hound

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. Adding an SPN and quickly deleting it is less common but may be part of legitimate action. 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 $user$ was set and shortly deleted	40	50	80

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: 2