ServicePrincipalNames Discovery with PowerShell
Description
The following analytic identifies powershell.exe
usage, using Script Block Logging EventCode 4104, 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.
The following analytic identifies the use of KerberosRequestorSecurityToken class within the script block. Using .NET System.IdentityModel.Tokens.KerberosRequestorSecurityToken class in PowerShell is the equivelant of using setspn.exe.
During triage, review parallel processes for further suspicious activity.
- Type: TTP
-
Product: Splunk Behavioral Analytics
- Last Updated: 2024-02-01
- Author: Michael Haag, Splunk
- ID: 043f07a0-7fd8-40e2-b526-80406fb59abb
Annotations
Kill Chain Phase
- Exploitation
NIST
- DE.CM
CIS20
- CIS 10
CVE
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$main = from source
| eval timestamp = time
| eval metadata_uid = metadata.uid
| eval device_hostname = device.hostname
| eval process_file = process.file
| eval process_file_path = process_file.path
| eval process_uid = process.uid
| eval process_cmd_line = process.cmd_line
| eval actor_user = actor.user
| eval actor_user_uid = actor_user.uid
| where match(process_cmd_line, /(?i)KerberosRequestorSecurityToken/)=true --finding_report--
Macros
The SPL above uses the following Macros:
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.
- device.hostname
- process.file.path
- process.uid
- process.cmd_line
- actor.user.uid
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
source | version: 2