Detecting NTLM Relay with Event Correlation Agent Skill

Detect NTLM relay attacks (T1557.001) by correlating Windows Event 4624 LogonType 3 for IP-to-hostname mismatches, identifying…

Context cost
13.3k tokensestimated from the bundle, loaded when it triggers
Bundle
5 files · 91.6 kB2 scripts among them — read before you run
Licence
Apache-2.0the author’s own terms
Last change
—v1.0
Servers it uses
Noneruns standalone

What it does

Detect NTLM relay attacks (T1557.001) by correlating Windows Event 4624 LogonType 3 for IP-to-hostname mismatches, identifying Responder/LLMNR poisoning artifacts, auditing SMB/LDAP signing, and flagging NTLMv2-to-NTLMv1 downgrades. Use for hunting credential relay in NTLM-enabled AD, investigating auth-source anomalies, building SIEM correlation rules, or responding to PetitPotam/DFSCoerce/PrinterBug alerts.

What this skill changes about the agent has not been set out here as a list. Its SKILL.md, shown below, says it in the author’s own words.

securitytesting

The skill itself

A skill is instructions the model reads, so you can see what you are getting: below is the start of its SKILL.md. The front matter loads with every session, the body loads when the skill triggers, and the whole file comes with the install.

SKILL.md34.7 kB · preview
--- name: detecting-ntlm-relay-with-event-correlation domain: cybersecurity subdomain: threat-hunting tags: - threat-hunting - NTLM-relay - event-correlation - T1557.001 - Event-4624 - Responder - SMB-signing - LDAP-signing - NTLM-downgrade - PetitPotam - Active-Directory version: '1.0' author: mukul975 license: Apache-2.0 atlas_techniques: - AML.T0051 - AML.T0054 - AML.T0056 - AML.T0020 d3fend_techniques: - Application Protocol Command Analysis - Network Isolation - Network Traffic Analysis - Client-server Payload Profiling - Network Traffic Community Deviation nist_ai_rmf: - MEASURE-2.7 - MEASURE-2.5 - GOVERN-6.1 - MAP-5.1 nist_csf: - DE.CM-01 - DE.AE-02 - DE.AE-07 - ID.RA-05 mitre_attack: - T1046 - T1057 - T1082 - T1083 - T1069 ---
50# Detecting NTLM Relay with Event Correlation
51
52> **Authorized Testing Disclaimer**: The offensive techniques and attack simulations described in this skill are intended exclusively for authorized penetration testing, red team engagements, purple team exercises, and security research conducted with explicit written permission from the system owner. Unauthorized use of these techniques against systems you do not own or have permission to test is illegal and unethical. Always operate within the scope of your engagement and comply with applicable laws and regulations.
53
54## Overview
55
56NTLM relay attacks intercept NTLM authentication messages and forward them to a target service to gain unauthorized access. Attackers use tools like Responder for LLMNR/NBT-NS/mDNS poisoning, ntlmrelayx (Fox-IT/Impacket) for multi-protocol relay, and coercion techniques like PetitPotam (MS-EFSRPC) and DFSCoerce to force authentication from high-value targets like domain controllers. This skill provides a comprehensive event correlation framework using Windows Security Event 4624 LogonType 3 analysis, IP-to-hostname mismatch detection, Responder traffic identification, SMB/LDAP signing audit, and NTLM downgrade detection to identify relay attacks across Active Directory environments.
57
58## When to Use
59
60- Hunting for credential relay activity in Active Directory environments where NTLM authentication is still in use
61- Investigating alerts for authentication anomalies where the source IP does not match the expected workstation
62- Auditing SMB signing and LDAP signing enforcement to assess exposure to relay attacks
63- Detecting NTLM downgrade attacks where NTLMv2 is forced to NTLMv1 for easier offline cracking or relay
64- Building SIEM correlation rules for MITRE ATT&CK T1557.001 (LLMNR/NBT-NS Poisoning and SMB Relay)
65- Responding to PetitPotam, DFSCoerce, or PrinterBug coercion alerts that may precede relay attacks
66- During purple team exercises validating NTLM relay detection and SMB signing enforcement
67
68**Do not use** without centralized Windows Security Event Log collection, as a substitute for enforcing SMB signing and Extended Protection for Authentication (EPA) which prevent relay attacks at the protocol level, or without an IP-to-hostname inventory for correlation.
This is a preview of SKILL.md. Download or install the skill to get the whole thing.
In the file
SKILL.md4,241 words
Files5
LicenceApache-2.0
Why you can read it

Nothing in a skill executes. The client loads the text and the model follows it, so a skill can be audited the way a runbook is — by reading it.

What it costs in context

Skills are not billed by the call. They are paid for in context: every token the instructions occupy is a token your code, your diff and your conversation cannot use. Here is what this one takes and when it takes it.

≈290
always loaded
The name and description, so the model knows the skill exists and when to reach for it.
13,060
on trigger
The instruction body and 4 supporting files, read only when the skill fires.
6.7%
of a 200k window
Ten skills this size would take about 67% of the window before you open a file.
050k100k150k200k context window

13.3k tokens, estimated from the bundle at four bytes to the token, held for the rest of the session once it triggers. Heavy. Teams tend to install this one per project rather than globally, and load it only when the job comes up.

Servers bill, skills cost

A server charges by the month. A skill charges once per session, in context, and then keeps charging it for as long as the session lives.

Before and after

The same question, put to the same model twice: once as it comes, and once with these instructions loaded.

No worked example has been published for this skill yet.

The procedure it runs

The procedure has not been set out here step by step. It is in the body of its SKILL.md: the start of it is shown above, and the whole file comes with the install.

Prose, not code

These steps are written for a model to follow, not executed by a runtime. It can still be told to skip one, and it will say so when it does.

Servers it uses

None. This skill calls no MCP servers at all.

Everything it needs is in the instructions, so it works in a project with nothing connected — the model reads the file and changes how it works with what it can already reach.

Its SKILL.md does not declare which tools it asks the agent for, so what it touches is whatever the instructions themselves ask for — read them before you install it.

What it asks for
Writes filesnot declared
Network accessnot declared

This SKILL.md carries no allowed-tools line, so neither is declared. A skill grants no permissions of its own — it can only ask for tools your client already has.

What it will not do

Every skill is narrow, and the useful ones say where they stop. These are the jobs this one is the wrong tool for.

What this skill is not for has not been published here. Nothing is implied by that: it is a section the author has not filled in.

What is in the bundle

5 files, 91.6 kB on disk. Mostly text — the instructions the model reads — with 2 scripts in it that your client would run only if the instructions tell it to. 1 file of its source is not in the download — listed after these, with why.

  • SKILL.md34.7 kB
  • LICENSE11.3 kB
  • references/api-reference.md7.4 kB
  • scripts/agent.py14.7 kB
  • scripts/detect_ntlm_relay.py23.5 kB

Not in the download

Not carried is a type a skill download does not hold. Take it from its source.

  • scripts/audit_smb_signing.ps1not carried
What is not in it

A skill installs nothing and depends on nothing: it is a folder your client reads. This one carries 2 scripts beside the text, so the download is 5 files — not the whole of its source: 1 file is left out. It is listed under the files, with why. The Apache-2.0 licence covers the templates and examples as well as the instructions.

Install

Installing copies the bundle into your project. Nothing runs at install time — the files sit on disk until the model reads them.

# Detecting NTLM Relay with Event Correlation · 13.3k tokens when loaded · macOS, Linux mkdir -p .claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/detecting-ntlm-relay-with-event-correlation/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/detecting-ntlm-relay-with-event-correlation" ] && { [ ! -e .claude/skills/detecting-ntlm-relay-with-event-correlation ] || { mv .claude/skills/detecting-ntlm-relay-with-event-correlation "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/detecting-ntlm-relay-with-event-correlation" .claude/skills/ && echo "Installed .claude/skills/detecting-ntlm-relay-with-event-correlation"
On Windows, or any OS with Node 20+
npx mcprush@latest skill add mukul975/detecting-ntlm-relay-with-event-correlation

Windows PowerShell says 'running scripts is disabled on this system'? Run Set-ExecutionPolicy -Scope CurrentUser RemoteSigned once, or type npx.cmd instead of npx (codex.cmd, gemini.cmd, grok.cmd likewise). PowerShell 7 needs neither. Writes to .claude/skills/detecting-ntlm-relay-with-event-correlation/ in the current project. For every project instead, run mkdir -p ~/.claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/detecting-ntlm-relay-with-event-correlation/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/detecting-ntlm-relay-with-event-correlation" ] && { [ ! -e ~/.claude/skills/detecting-ntlm-relay-with-event-correlation ] || { mv ~/.claude/skills/detecting-ntlm-relay-with-event-correlation "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/detecting-ntlm-relay-with-event-correlation" ~/.claude/skills/ && echo "Installed ~/.claude/skills/detecting-ntlm-relay-with-event-correlation" (macOS, Linux) — or add --global to the npx line. The curl line replaces .claude/skills/detecting-ntlm-relay-with-event-correlation/ only after the download succeeds, so files left there by another skill of the same name, or by an older release, do not mix in. A copy already there is moved aside, not deleted, and the line prints where. Not in this download: 1 file of its source (which one, and why). Take it from its source.

Which clients pick it up on their own

A skill is a folder of text. Most of these read a skills folder and pick it up without being told; the rest take the same folder another way — an upload in the app, a parameter on an API call — and then choose it by its description just the same.

Claude Code.claude/skills/
Claude DesktopCustomize › Skills
ChatGPTSkills › Create › Upload
Cursor.cursor/skills/
VS Code.github/skills/
Codex CLI.agents/skills/
Gemini CLI.gemini/skills/
Grok Build.grok/skills/
Microsoft CopilotSkills › Upload a skill
PerplexityComputer › Skills › Upload a skill
DeepSeek Harness.dsh/skills/
Zed.agents/skills/
Devin Desktop.devin/skills/
Windsurf (legacy).windsurf/skills/
OpenAI Agents SDKInstructions or sandbox Skills
HTTP / APIa request parameter
This release
Version1.0
Publishedno release date on file
PriceFree
Referencemukul975/detecting-ntlm-relay-with-event-correlation

Versions

v1.0 is what is on the shelf; no release here carries a date. Instructions change more often than APIs do — a skill can be rewritten entirely without anything it depends on moving.

v1.0
  • No earlier releases have been published to the marketplace.
Pinning

The install command always fetches the release that is current the day you run it — v1.0 today — and cannot ask for an earlier one. The copy on your disk does not change until you run it again.

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