detecting-golden-ticket-attacks-in-kerberos-logs

Imported from mukul975/anthropic-cybersecurity-skills (skills/detecting-golden-ticket-attacks-in-kerberos-logs/SKILL.md). Install upstream with npx skills add mukul975/anthropic-cybersecurity-skills --skill detecting-golden-ticket-attacks-in-kerberos-logs. Copyright stays with the author (Apache-2.0).

Detecting Golden Ticket Attacks in Kerberos Logs

When to Use

• When KRBTGT account hash may have been compromised via DCSync or NTDS.dit extraction
• When hunting for forged Kerberos tickets used for persistent domain access
• After incident response reveals credential theft at the domain level
• When investigating impossible logon patterns (users logging in from multiple locations simultaneously)
• During post-breach assessment to determine if Golden Tickets are in use

Prerequisites

• Windows Security Event IDs 4768, 4769, 4771 on domain controllers
• Kerberos policy configuration knowledge (max ticket lifetime, encryption types)
• Domain controller audit policy enabling Kerberos Service Ticket Operations
• SIEM with ability to correlate Kerberos events across multiple DCs

Workflow

1. Monitor TGT Requests (Event 4768): Track Kerberos authentication service requests. Golden Tickets bypass the AS-REQ/AS-REP exchange entirely, so the absence of 4768 before 4769 is suspicious.
2. Detect Encryption Type Anomalies: Golden Tickets often use RC4 (0x17) encryption. If your domain enforces AES (0x12), any RC4 TGT is a red flag. Monitor TicketEncryptionType in Event 4769.
3. Check Ticket Lifetime Anomalies: Default Kerberos TGT lifetime is 10 hours with 7-day renewal. Golden Tickets can be forged with 10-year lifetimes. Detect tickets with durations exceeding policy.
4. Hunt for Non-Existent SIDs: Golden Tickets can include arbitrary SIDs (including non-existent accounts or groups). Correlate TGS requests against known AD SID inventory.
5. Detect TGS Without Prior TGT: When a service ticket (4769) appears without a preceding TGT request (4768) from the same IP/account, this may indicate a pre-existing Golden Ticket.
6. Monitor KRBTGT Password Age: Track when KRBTGT was last reset. If KRBTGT hash hasn't changed since a known compromise, Golden Tickets from that period remain valid.
7. Validate PAC Signatures: With KB5008380+ and PAC validation enforcement, domain controllers reject forged PACs. Monitor for Kerberos failures indicating PAC validation errors.

Detection Queries

Splunk -- RC4 Encryption in Kerberos TGS

index=wineventlog EventCode=4769
| where TicketEncryptionType="0x17"
| where ServiceName!="krbtgt"
| stats count by TargetUserName ServiceName IpAddress TicketEncryptionType Computer
| where count > 5
| sort -count

Splunk -- TGS Without Prior TGT

index=wineventlog (EventCode=4768 OR EventCode=4769)
| stats earliest(_time) as first_tgt by TargetUserName IpAddress EventCode
| eventstats earliest(eval(if(EventCode=4768, first_tgt, null()))) as tgt_time by TargetUserName IpAddress
| where EventCode=4769 AND (isnull(tgt_time) OR first_tgt < tgt_time)
| table TargetUserName IpAddress first_tgt tgt_time

KQL -- Golden Ticket Indicators

SecurityEvent
| where EventID == 4769
| where TicketEncryptionType == "0x17"
| where ServiceName != "krbtgt"
| summarize Count=count() by TargetUserName, IpAddress, ServiceName
| where Count > 5

Common Scenarios

1. Post-DCSync Golden Ticket: After extracting KRBTGT hash, attacker forges TGT with Domain Admin SID, valid for months until KRBTGT is rotated twice.
2. RC4 Downgrade: Golden Ticket forged with RC4 encryption in an AES-only environment, detectable by encryption type mismatch.
3. Cross-Domain Golden Ticket: Forged inter-realm TGT used to pivot between AD domains/forests.
4. Persistence After Remediation: Golden Tickets surviving password resets because KRBTGT was only rotated once (both current and previous hashes are valid).

Output Format

Hunt ID: TH-GOLDEN-[DATE]-[SEQ]
Suspected Account: [Account using forged ticket]
Source IP: [Client IP]
Target Service: [SPN accessed]
Encryption Type: [RC4/AES128/AES256]
Anomaly: [No prior TGT/RC4 in AES environment/Extended lifetime]
KRBTGT Last Reset: [Date]
Risk Level: [Critical]