What it does. Detect Kerberos Pass-the-Ticket (PtT) attacks by analyzing Windows Event IDs 4768, 4769, and 4771 for anomalous ticket usage patterns, with detection queries for Splunk and Elastic SIEM. Use when investigating incidents involving stolen or replayed Kerberos tickets, building detection rules or threat hunting queries for ticket abuse, or validating SOC monitoring coverage for credential-theft attack techniques. Part of mukul975/Anthropic-Cybersecurity-Skills (817 security skills) (mukul975/Anthropic-Cybersecurity-Skills).

Install

• npx skills add mukul975/Anthropic-Cybersecurity-Skills --skill detecting-pass-the-ticket-attacks, or copy the skill folder into ~/.claude/skills/detecting-pass-the-ticket-attacks/.
• Raw file: curl -sL https://raw.githubusercontent.com/mukul975/Anthropic-Cybersecurity-Skills/HEAD/skills/detecting-pass-the-ticket-attacks/SKILL.md

SKILL.md (verbatim)

name: detecting-pass-the-ticket-attacks
description: Detect Kerberos Pass-the-Ticket (PtT) attacks by analyzing Windows Event IDs 4768, 4769, and 4771 for anomalous ticket usage patterns, with detection queries for Splunk and Elastic SIEM. Use when investigating incidents involving stolen or replayed Kerberos tickets, building detection rules or threat hunting queries for ticket abuse, or validating SOC monitoring coverage for credential-theft attack techniques.
domain: cybersecurity
subdomain: threat-detection
tags:
- kerberos
- pass-the-ticket
- active-directory
- splunk
- elastic
- credential-theft
- windows-security
version: '1.0'
author: mahipal
license: Apache-2.0
d3fend_techniques:
- Token Binding
- Execution Isolation
- Restore Access
- Application Protocol Command Analysis
- Process Termination
nist_csf:
- DE.CM-01
- DE.AE-02
- DE.AE-06
- ID.RA-05
mitre_attack:
- T1078
- T1190
- T1059
- T1003
- T1110

Detecting Pass-the-Ticket Attacks

Overview

Pass-the-Ticket (PtT) is a credential theft technique (MITRE ATT&CK T1550.003) where adversaries steal Kerberos tickets (TGT or TGS) from one system and replay them on another to authenticate without knowing the user's password. This skill teaches detection of PtT attacks by correlating Windows Security Event IDs 4768 (TGT request), 4769 (TGS request), and 4771 (pre-authentication failure) for anomalies such as ticket reuse across different hosts, RC4 encryption downgrades, and unusual service ticket request volumes.

When to Use

• When investigating security incidents that require detecting pass the ticket attacks
• When building detection rules or threat hunting queries for this domain
• When SOC analysts need structured procedures for this analysis type
• When validating security monitoring coverage for related attack techniques

Prerequisites

• Windows Domain Controller with advanced audit policy enabled (Audit Kerberos Authentication Service, Audit Kerberos Service Ticket Operations)
• Splunk or Elastic SIEM ingesting Windows Security event logs
• Sysmon deployed on endpoints for supplementary process telemetry
• Python 3.8+ with requests library

Steps

1. Enable Kerberos audit logging on Domain Controllers via Group Policy
2. Forward Event IDs 4768, 4769, and 4771 to SIEM platform
3. Deploy detection rules for RC4 encryption downgrade (TicketEncryptionType 0x17)
4. Create correlation rule for ticket reuse across multiple source IPs
5. Build baseline of normal TGS request volume per user/host
6. Alert on standard deviation anomalies in ticket request patterns
7. Investigate flagged events with enrichment from Active Directory

Expected Output

JSON report containing detected PtT indicators including anomalous ticket requests, RC4 downgrades, cross-host ticket reuse events, and risk-scored users with MITRE ATT&CK technique mapping.

Other files in this skill

• LICENSE
• references/api-reference.md
• scripts/agent.py

references/api-reference.md (verbatim)

Pass-the-Ticket Detection API Reference

Windows Security Event IDs

Event ID 4768 - TGT Requested

Key Fields:
  TargetUserName      - Account requesting TGT
  TargetDomainName    - Domain of account
  IpAddress           - Source IP of request
  TicketEncryptionType - 0x12 (AES256), 0x17 (RC4-HMAC)
  PreAuthType         - 15 (PA-ENC-TIMESTAMP)

Event ID 4769 - TGS Requested

Key Fields:
  TargetUserName      - Account using the ticket
  ServiceName         - SPN of requested service
  IpAddress           - Source IP
  TicketEncryptionType - 0x17 indicates RC4 downgrade
  TicketOptions       - Kerberos ticket flags

Event ID 4771 - Kerberos Pre-Authentication Failed

Key Fields:
  TargetUserName      - Account that failed
  IpAddress           - Source of failure
  Status              - 0x18 (wrong password), 0x12 (expired)

Splunk SPL Queries

RC4 Encryption Downgrade Detection

index=wineventlog sourcetype="WinEventLog:Security" EventCode=4769
  TicketEncryptionType=0x17
| stats count by TargetUserName, IpAddress, ServiceName
| where count > 3

Cross-Host Ticket Reuse

index=wineventlog EventCode=4769
| stats dc(IpAddress) as ip_count, values(IpAddress) as ips
  by TargetUserName
| where ip_count > 1
| sort -ip_count

TGS Volume Anomaly

index=wineventlog EventCode=4769
| bin _time span=1h
| stats count by TargetUserName, _time
| eventstats avg(count) as avg_count, stdev(count) as sd by TargetUserName
| where count > avg_count + (3 * sd)

Elastic / KQL Queries

RC4 Downgrade in Elastic

event.code: "4769" AND winlog.event_data.TicketEncryptionType: "0x17"

Cross-Host Reuse in Elastic

POST security-*/_search
{
  "size": 0,
  "query": { "term": { "event.code": "4769" } },
  "aggs": {
    "by_user": {
      "terms": { "field": "winlog.event_data.TargetUserName" },
      "aggs": {
        "unique_ips": { "cardinality": { "field": "source.ip" } }
      }
    }
  }
}

MITRE ATT&CK Mapping

CLI Usage

# Parse exported event log XML and detect PtT indicators
python agent.py --evtx-xml security_events.xml --output report.json

# Show Splunk detection queries
python agent.py --show-splunk

# Custom thresholds
python agent.py --evtx-xml events.xml --tgs-threshold 30 --preauth-threshold 5

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