Name:PetitPotam Suspicious Kerberos TGT Request id:e3ef244e-0a67-11ec-abf2-acde48001122 version:11 date:None 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' analytic_story:['PetitPotam NTLM Relay on Active Directory Certificate Services', 'Active Directory Kerberos Attacks']
