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Anthropic-Cybersecurity-Skills/skills/hunting-for-ntlm-relay-attacks/SKILL.md
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mukul975 cb8d79e068 Map all 754 skills to MITRE ATT&CK v19.1
- Add validated mitre_attack frontmatter to all 754 skills (286 distinct
  techniques), verified against MITRE ATT&CK v19.1 via the official
  mitreattack-python library: 0 revoked, deprecated, or invalid IDs
- Curate precise per-skill technique IDs for forensics, malware-analysis,
  threat-intel, and red-team skills (e.g. DCSync -> T1003.006,
  Kerberoasting -> T1558.003, Pass-the-Ticket -> T1550.003)
- Reconcile v19.1 tactic restructuring: Defense Evasion split into
  Stealth (TA0005) and Defense Impairment (TA0112); revoked T1562.*
  family and T1070.001/.002 remapped to active equivalents (T1685.*)
- Normalize word-split tags across 35 skills (remove filename-derived
  stopword tags, add semantic cybersecurity tags)
- Add api-reference.md for 3 skills that were missing it
- Update README ATT&CK section with accurate v19.1 tactic distribution
2026-06-01 12:13:29 +02:00

2.7 KiB

name, description, domain, subdomain, tags, version, author, license, d3fend_techniques, nist_csf, mitre_attack
name description domain subdomain tags version author license d3fend_techniques nist_csf mitre_attack
hunting-for-ntlm-relay-attacks Detect NTLM relay attacks by analyzing Windows Event 4624 logon type 3 with NTLMSSP authentication, identifying IP-to-hostname mismatches, Responder traffic signatures, SMB signing status, and suspicious authentication patterns across the domain. cybersecurity threat-hunting
NTLM-relay
Windows-events
Event-4624
NTLMSSP
Responder
SMB-signing
credential-access
T1557.001
Active-Directory
1.0 mahipal Apache-2.0
Application Protocol Command Analysis
Network Isolation
Network Traffic Analysis
Client-server Payload Profiling
Network Traffic Community Deviation
DE.CM-01
DE.AE-02
DE.AE-07
ID.RA-05
T1046
T1057
T1082
T1083
T1003

Hunting for NTLM Relay Attacks

Overview

NTLM relay attacks intercept and forward NTLM authentication messages to gain unauthorized access to network resources. Attackers use tools like Responder for LLMNR/NBT-NS poisoning and ntlmrelayx for credential relay. This skill detects relay activity by querying Windows Security Event 4624 (successful logon) for type 3 network logons with NTLMSSP authentication, identifying mismatches between WorkstationName and source IpAddress, detecting rapid multi-host authentication from single accounts, and auditing SMB signing configuration across domain hosts.

When to Use

  • When investigating security incidents that require hunting for ntlm relay 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

  • Python 3.9+ with Windows Event Log access or exported logs
  • Windows Security audit logging enabled (Event ID 4624, 4625, 5145)
  • Network access for SMB signing status checks

Key Detection Areas

  1. IP-hostname mismatch — WorkstationName in Event 4624 does not resolve to the source IpAddress
  2. NTLMSSP authentication — logon events using NTLM instead of Kerberos from domain-joined hosts
  3. Machine account relay — computer accounts (ending in $) authenticating from unexpected IPs
  4. Rapid authentication — single account authenticating to multiple hosts within seconds
  5. Named pipe access — Event 5145 showing access to Spoolss, lsarpc, netlogon, samr pipes
  6. SMB signing disabled — hosts not enforcing SMB signing, enabling relay attacks

Output

JSON report with suspected relay events, IP-hostname correlation anomalies, SMB signing audit results, and MITRE ATT&CK mapping to T1557.001.