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The following analytic detects the addition of Service Principal Names (SPNs) HOST and RestrictedKrbHost to a computer account, indicative of KrbRelayUp behavior. This detection leverages Windows Security Event Logs, specifically EventCode 4741, to identify changes in SPNs. This activity is significant as it is commonly associated with Kerberos-based attacks, which can be used to escalate privileges or perform lateral movement within a network. If confirmed malicious, this behavior could allow an attacker to impersonate services, potentially leading to unauthorized access to sensitive resources.

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

  • Last Updated: 2024-05-18
  • Author: Michael Haag, Splunk
  • ID: 9a3e57e7-33f4-470e-b25d-165baa6e8357




ID Technique Tactic
T1558 Steal or Forge Kerberos Tickets Credential Access
Kill Chain Phase
  • Exploitation
  • DE.CM
  • CIS 10
`wineventlog_security` EventCode=4741 NewUacValue="0x80" ServicePrincipalNames IN ("*HOST/*","*RestrictedKrbHost/*") 
| stats count min(_time) as firstTime max(_time) as lastTime values(EventCode),values(TargetDomainName),values(PrimaryGroupId), values(OldUacValue), values(NewUacValue),values(SamAccountName),values(DnsHostName),values(ServicePrincipalNames) by dest Logon_ID subject 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_computer_account_with_spn_filter`


The SPL above uses the following Macros:

:information_source: windows_computer_account_with_spn_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
  • EventCode
  • MSADChangedAttributes
  • New_UAC_Value
  • Security_ID
  • Account_Domain
  • SAM_Account_Name
  • DNS_Host_Name
  • Logon_Id

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 add these SPNs to Computer Accounts, filtering may be needed.

Associated Analytic Story


Risk Score Impact Confidence Message
64.0 80 80 A Computer Account was created with SPNs related to Kerberos on $dest$, possibly indicative of Kerberos relay attack.

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


Test Dataset

Replay any dataset to Splunk Enterprise by using our tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

source | version: 3