The following analytic identifes a Computer Account creating a new Computer Account with specific a Service Principle Name - "RestrictedKrbHost". The RestrictedKrbHost service class allows client applications to use Kerberos authentication when they do not have the identity of the service but have the server name.
- Type: TTP
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2022-04-27
- Author: Michael Haag, Splunk
- ID: 97a8dc5f-8a7c-4fed-9e3e-ec407fd0268a
Kill Chain Phase
- CIS 3
- CIS 5
- CIS 16
1 2 3 4 5 `wineventlog_security` EventCode=4741 user_type=computer Subject_Account_Domain!="NT AUTHORITY" Message=*RestrictedKrbHost* | stats count min(_time) as firstTime max(_time) as lastTime by dest, subject, action ,src_user, user, Account_Name, Subject_Account_Name,Subject_Account_Domain | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `windows_computer_account_created_by_computer_account_filter`
The SPL above uses the following Macros:
windows_computer_account_created_by_computer_account_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
List of fields required to use this analytic.
How To Implement
To successfully implement this search, you need to be ingesting Windows Security Event Logs with 4741 EventCode enabled. The Windows TA is also required.
Known False Positives
It is possible third party applications may have a computer account that adds computer accounts, filtering may be required.
Associated Analytic Story
|30.0||50||60||A Computer Account created a Computer Account on $dest$, possibly indicative of Kerberos relay attack.|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
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