ServicePrincipalNames Discovery with PowerShell

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Description

The following analytic detects the use of powershell.exe to query the domain for Service Principal Names (SPNs) using Script Block Logging EventCode 4104. It identifies the use of the KerberosRequestorSecurityToken class within the script block, which is equivalent to using setspn.exe. This activity is significant as it often precedes kerberoasting or silver ticket attacks, which can lead to credential theft. If confirmed malicious, attackers could leverage this information to escalate privileges or persist within the environment.

• Type: TTP

• Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud

• Last Updated: 2024-05-11
• Author: Michael Haag, Splunk
• ID: 13243068-2d38-11ec-8908-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

`powershell` EventCode=4104 ScriptBlockText="*KerberosRequestorSecurityToken*" 
| stats count min(_time) as firstTime max(_time) as lastTime by ScriptBlockText Opcode Computer UserID EventCode 
| rename Computer as dest 
| rename UserID as user 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `serviceprincipalnames_discovery_with_powershell_filter`

Macros

The SPL above uses the following Macros:

• powershell
• security_content_ctime

serviceprincipalnames_discovery_with_powershell_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
• ScriptBlockText
• Opcode
• Computer
• UserID
• EventCode

How To Implement

To successfully implement this analytic, you will need to enable PowerShell Script Block Logging on some or all endpoints. Additional setup here https://docs.splunk.com/Documentation/UBA/5.0.4.1/GetDataIn/AddPowerShell#Configure_module_logging_for_PowerShell.

Known False Positives

False positives should be limited, however filter as needed.

Associated Analytic Story

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

RBA

Risk Score	Impact	Confidence	Message
80.0	80	100	An instance of attempting to identify service principle detected on $dest$ 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://docs.microsoft.com/en-us/dotnet/api/system.identitymodel.tokens.kerberosrequestorsecuritytoken?view=netframework-4.8
• 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
• https://docs.splunk.com/Documentation/UBA/5.0.4.1/GetDataIn/AddPowerShell#Configure_module_logging_for_PowerShell.
• https://blog.palantir.com/tampering-with-windows-event-tracing-background-offense-and-defense-4be7ac62ac63
• https://static1.squarespace.com/static/552092d5e4b0661088167e5c/t/59c1814829f18782e24f1fe2/1505853768977/Windows+PowerShell+Logging+Cheat+Sheet+ver+Sept+2017+v2.1.pdf
• https://www.crowdstrike.com/blog/investigating-powershell-command-and-script-logging/

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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