# 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.

- Skill: `mukul975/hunting-for-ntlm-relay-attacks` (Agent Skill, multi-file: 4 files)
- Install (CLI): `npx skillmds add mukul975/hunting-for-ntlm-relay-attacks`
- Raw SKILL.md: https://api.skillmd.com/api/skills/mukul975/hunting-for-ntlm-relay-attacks/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Security, Coding & Dev Tools, Incident Response, Vulnerability Scanning
- Tags: Mitre Attck, Ntlm Relay, Ntlmssp, Responder, Smb Signing, Threat Hunting, Windows Event 4624
- License: Apache-2.0
- Author: mukul975 (https://skillmd.com/u/mukul975)
- Updated: 2026-07-06
- Page: https://skillmd.com/skills/mukul975/hunting-for-ntlm-relay-attacks

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# 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.