PetitPotam Suspicious Kerberos TGT Request

name: PetitPotam Suspicious Kerberos TGT Request
id: e3ef244e-0a67-11ec-abf2-acde48001122
version: 11
creation_date: '2021-09-01'
modification_date: '2026-07-04'
author: Michael Haag, Mauricio Velazco, Splunk
status: production
type: TTP
description: The following analytic detects a suspicious Kerberos Ticket Granting Ticket (TGT) request, identified by Event Code 4768. This detection leverages Windows Security Event Logs to identify TGT requests with unusual fields, which may indicate the use of tools like Rubeus following the exploitation of CVE-2021-36942 (PetitPotam). This activity is significant as it can signal an attacker leveraging a compromised certificate to request Kerberos tickets, potentially leading to unauthorized access. If confirmed malicious, this could allow attackers to escalate privileges and persist within the environment, posing a severe security risk.
data_source:
    - Windows Event Log Security 4768
search: |-
    `wineventlog_security`
    EventCode=4768
    src!="::1"
    TargetUserName=*$
    CertThumbprint!=""
    PreAuthType=2
    | stats count min(_time) as firstTime
                  max(_time) as lastTime
      BY dest TargetUserName PreAuthType CertThumbprint src action
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `petitpotam_suspicious_kerberos_tgt_request_filter`
how_to_implement: |-
    The following analytic requires Event Code 4768. Ensure that it is logging no Domain Controllers and appearing in Splunk.
known_false_positives: |-
    False positives are possible if the environment is using certificates for authentication, since PreAuthType 2 can appear on some initial or fallback authentication flows alongside a populated certificate field.
    Tune further based on observed authentication patterns in the environment.
references:
    - https://www.ultimatewindowssecurity.com/securitylog/encyclopedia/event.aspx?eventid=4768
    - https://isc.sans.edu/forums/diary/Active+Directory+Certificate+Services+ADCS+PKI+domain+admin+vulnerability/27668/
    - https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-10/security/threat-protection/auditing/event-4768#kerberos-preauthentication-types
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search  dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
finding:
    title: A Kerberos TGT was requested in a non-standard manner against $dest$, potentially related to CVE-2021-36942, PetitPotam.
    entity:
        field: dest
        type: system
        score: 50
analytic_story:
    - PetitPotam NTLM Relay on Active Directory Certificate Services
    - Active Directory Kerberos Attacks
asset_type: Endpoint
cve:
    - CVE-2021-36942
mitre_attack_id:
    - T1003
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1187/petitpotam/windows-xml-1.log
          source: XmlWinEventLog:Security
          sourcetype: XmlWinEventLog
      test_type: unit