threat-modelling

name	threat-modelling
description	Analyse repositories and deployed cloud infrastructure to produce STRIDE-based threat model documents with Mermaid architecture diagrams, prioritised threats, and recommendations. Use when a user asks to create a threat model, identify threats, assess attack surfaces, review an existing threat model, or update a threat model after system changes.
license	MIT
allowed-tools	Bash

Threat Modelling

Overview

This skill produces threat model documents by analysing codebases, infrastructure-as-code, and live cloud resources. It follows the STRIDE framework and the Microsoft Threat Modeling Fundamentals four-phase approach: Design, Break, Fix (recommendations only), and Verify.

This skill produces threat models. It does NOT implement fixes or perform penetration testing.

Capabilities

Capability	Action	Description
Analyse Repository	actions/analyse-repository.md	Scan codebase and IaC to map architecture and confirm a data flow diagram
Assess Infrastructure	actions/assess-infrastructure.md	Query live cloud resources via MCP servers to map architecture and confirm a data flow diagram
Generate Threat Model	actions/generate-threat-model.md	Apply STRIDE to a confirmed diagram, produce threat model diagram and document
Review Threat Model	actions/review-threat-model.md	Evaluate an existing threat model for completeness and accuracy
Update Threat Model	actions/update-threat-model.md	Revise an existing threat model based on system changes

Standards

Standard	File	Description
STRIDE Framework	standards/stride-framework.md	STRIDE threat categories and identification guidance
Document Template	standards/document-template.md	Threat model document structure and Mermaid diagram format
Checklist	standards/checklist.md	Consolidated compliance and quality checklist

Principles

1. Analyse, Never Fix

This skill identifies and documents threats. It recommends mitigations but never implements fixes itself. The output is a document, not a code change.

2. Confirm Before Proceeding

Always confirm the architecture diagram with the user before identifying threats. After threat identification, work with the user to prioritise, resolve, or remove items from the model.

3. Follow STRIDE Systematically

Apply all six STRIDE categories to every component and data flow. Do not skip categories — document "No threats identified" where appropriate rather than omitting the analysis.

4. Cloud-Agnostic

When assessing deployed infrastructure, detect available MCP servers or ask the user which cloud provider to query. Do not assume a specific cloud platform.

5. Prioritise by Risk

All identified threats must be prioritised. Use a consistent risk-rating approach combining likelihood and impact so the user can focus on what matters most.

Scope Boundaries

In Scope	Out of Scope
Repository and IaC analysis	Implementing security fixes
Live cloud infrastructure assessment via MCP	Penetration testing
STRIDE-based threat identification	Security patching
Architecture diagrams (Mermaid)	Code vulnerability scanning
Threat prioritisation with user	Automated remediation
Mitigation recommendations	Compliance auditing
Reviewing existing threat models
Updating existing threat models

Usage

1. Load this skill manifest
2. Identify the required capability (analyse, assess, review, or update)
3. Load the bundled standards from standards/
4. Execute the action following actions/<capability>.md

References

• Microsoft Threat Modeling Fundamentals
• STRIDE Framework
• Threat Modeling Phases
• Data-Flow Diagram Elements
• Prioritise Issues and Apply Security Controls