Suspicious Kerberos Service Ticket Request

name: Suspicious Kerberos Service Ticket Request
id: 8b1297bc-6204-11ec-b7c4-acde48001122
version: 12
creation_date: '2021-12-20'
modification_date: '2026-05-13'
author: Mauricio Velazco, Splunk
status: production
type: TTP
description: The following analytic detects suspicious Kerberos Service Ticket (TGS) requests where the requesting account name matches the service name, potentially indicating an exploitation attempt of CVE-2021-42278 and CVE-2021-42287. This detection leverages Event ID 4769 from Domain Controller and Kerberos events. Such activity is significant as it may represent an adversary attempting to escalate privileges by impersonating a domain controller. If confirmed malicious, this could allow an attacker to take control of the domain controller, leading to complete domain compromise and unauthorized access to sensitive information.
data_source:
    - Windows Event Log Security 4769
search: |-
    `wineventlog_security` EventCode=4769
      | eval isSuspicious = if(lower(ServiceName) = lower(mvindex(split(TargetUserName,"@"),0)),1,0)
      | where isSuspicious = 1
      | rename Computer as dest
      | rename TargetUserName as user
      | table _time, dest, src_ip, user, ServiceName, Error_Code, isSuspicious
      | `suspicious_kerberos_service_ticket_request_filter`
how_to_implement: To successfully implement this search, you need to be ingesting Domain Controller and Kerberos events. The Advanced Security Audit policy setting `Audit Kerberos Authentication Service` within `Account Logon` needs to be enabled.
known_false_positives: We have tested this detection logic with ~2 million 4769 events and did not identify false positives. However, they may be possible in certain environments. Filter as needed.
references:
    - https://exploit.ph/cve-2021-42287-cve-2021-42278-weaponisation.html
    - https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-42278
    - https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-42287
    - https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-sfu/02636893-7a1f-4357-af9a-b672e3e3de13
finding:
    title: A suspicious Kerberos Service Ticket was requested by $user$ on host $dest$
    entity:
        field: dest
        type: system
        score: 50
analytic_story:
    - sAMAccountName Spoofing and Domain Controller Impersonation
    - Active Directory Kerberos Attacks
    - Active Directory Privilege Escalation
asset_type: Endpoint
cve:
    - CVE-2021-42287
    - CVE-2021-42278
mitre_attack_id:
    - T1078.002
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint