Name:Kerberos Service Ticket Request Using RC4 Encryption id:7d90f334-a482-11ec-908c-acde48001122 version:5 date:2024-09-30 author:Mauricio Velazco, Splunk status:production type:TTP Description:The following analytic detects Kerberos service ticket requests using RC4 encryption, leveraging Kerberos Event 4769. This method identifies potential Golden Ticket attacks, where adversaries forge Kerberos Granting Tickets (TGT) using the Krbtgt account NTLM password hash to gain unrestricted access to an Active Directory environment. Monitoring for RC4 encryption usage is significant as it is rare in modern networks, indicating possible malicious activity. If confirmed malicious, attackers could move laterally and execute code on remote systems, compromising the entire network. Note: This detection may be bypassed if attackers use the AES key instead of the NTLM hash. Data_source:
-Windows Event Log Security 4769
search:`wineventlog_security` EventCode=4769 ServiceName="*$" (TicketOptions=0x40810000 OR TicketOptions=0x40800000 OR TicketOptions=0x40810010) TicketEncryptionType=0x17 | stats count min(_time) as firstTime max(_time) as lastTime by dest, service, service_id, TicketEncryptionType, TicketOptions | `security_content_ctime(lastTime)` | `security_content_ctime(firstTime)` | `kerberos_service_ticket_request_using_rc4_encryption_filter`
how_to_implement:To successfully implement this search, you need to be ingesting Domain Controller and Kerberos events. The Advanced Security Audit policy setting `Audit Kerberos Authentication Service` within `Account Logon` needs to be enabled. known_false_positives:Based on Microsoft documentation, legacy systems or applications will use RC4-HMAC as the default encryption for Kerberos Service Ticket requests. Specifically, systems before Windows Server 2008 and Windows Vista. Newer systems will use AES128 or AES256. References: -https://attack.mitre.org/techniques/T1558/001/ -https://docs.microsoft.com/en-us/windows/security/threat-protection/auditing/event-4769 -https://adsecurity.org/?p=1515 -https://gist.github.com/TarlogicSecurity/2f221924fef8c14a1d8e29f3cb5c5c4a -https://en.hackndo.com/kerberos-silver-golden-tickets/ drilldown_searches: name:'View the detection results for - "$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$") starthoursago=168 | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`' earliest_offset:'$info_min_time$' latest_offset:'$info_max_time$' tags: analytic_story: - 'Active Directory Kerberos Attacks' - 'Active Directory Privilege Escalation' asset_type:Endpoint confidence:50 impact:90 message:A Kerberos Service TTicket request with RC4 encryption was requested from $dest$ mitre_attack_id: - 'T1558' - 'T1558.001' observable: name:'dest' type:'Endpoint' - role: - 'Victim' product: - 'Splunk Enterprise' - 'Splunk Enterprise Security' - 'Splunk Cloud' required_fields: - '_time' - 'EventCode' - 'Ticket_Options' - 'Ticket_Encryption_Type' - 'dest' - 'service' - 'service_id' risk_score:45 security_domain:endpoint
