ServicePrincipalNames Discovery with SetSPN

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Description

The following analytic identifies setspn.exe usage related to querying the domain for Service Principle Names. typically, this is a precursor activity related to kerberoasting or the silver ticket attack.
What is a ServicePrincipleName?
A service principal name (SPN) is a unique identifier of a service instance. SPNs are used by Kerberos authentication to associate a service instance with a service logon account. This allows a client application to request that the service authenticate an account even if the client does not have the account name.
Example usage includes the following \

1. setspn -T offense -Q / 1. setspn -T attackrange.local -F -Q MSSQLSvc/* 1. setspn -Q / > allspns.txt 1. setspn -q
   Values \
2. -F = perform queries at the forest, rather than domain level 1. -T = perform query on the specified domain or forest (when -F is also used) 1. -Q = query for existence of SPN
   During triage, review parallel processes for further suspicious activity.

• Type: TTP
• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
• Datamodel: Endpoint
• Last Updated: 2021-10-14
• Author: Michael Haag, Splunk
• ID: ae8b3efc-2d2e-11ec-8b57-acde48001122

Annotations

ATT&CK

ATT&CK

ID	Technique	Tactic
T1558.003	Kerberoasting	Credential Access

Kill Chain Phase

• Exploitation

NIST

• DE.CM

CIS20

• CIS 10

CVE

Search

| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where `process_setspn` (Processes.process="*-t*" AND Processes.process="*-f*") OR (Processes.process="*-q*" AND Processes.process="**/**") OR (Processes.process="*-q*") OR (Processes.process="*-s*") by Processes.dest Processes.user Processes.parent_process_name Processes.process_name Processes.original_file_name Processes.process Processes.process_id Processes.parent_process_id 
| `drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)`
| `serviceprincipalnames_discovery_with_setspn_filter`

Macros

The SPL above uses the following Macros:

• process_setspn
• security_content_ctime
• security_content_summariesonly

serviceprincipalnames_discovery_with_setspn_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

• _time
• Processes.dest
• Processes.user
• Processes.parent_process_name
• Processes.parent_process
• Processes.original_file_name
• Processes.process_name
• Processes.process
• Processes.process_id
• Processes.parent_process_path
• Processes.process_path
• Processes.parent_process_id

How To Implement

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

False positives may be caused by Administrators resetting SPNs or querying for SPNs. Filter as needed.

Associated Analytic Story

• Active Directory Discovery
• Active Directory Kerberos Attacks
• Active Directory Privilege Escalation

RBA

Risk Score	Impact	Confidence	Message
80.0	80	100	An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$ attempting to identify service principle names.

The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

• https://docs.microsoft.com/en-us/windows/win32/ad/service-principal-names
• https://www.ired.team/offensive-security-experiments/active-directory-kerberos-abuse/t1208-kerberoasting
• https://strontic.github.io/xcyclopedia/library/setspn.exe-5C184D581524245DAD7A0A02B51FD2C2.html
• https://attack.mitre.org/techniques/T1558/003/
• https://social.technet.microsoft.com/wiki/contents/articles/717.service-principal-names-spn-setspn-syntax.aspx
• https://web.archive.org/web/20220212163642/https://www.harmj0y.net/blog/powershell/kerberoasting-without-mimikatz/
• https://blog.zsec.uk/paving-2-da-wholeset/
• https://msitpros.com/?p=3113
• https://adsecurity.org/?p=3466

Test Dataset

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

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