threat-modelling

# Threat Modelling ## Overview This skill produces threat model documents by analysing codebases, infrastructure-as-code, and live cloud resources. It follows the [STRIDE framework](https://learn.microsoft.com/en-us/training/modules/tm-use-a-framework-to-identify-threats-and-find-ways-to-reduce-or-eliminate-risk/) and the [Microsoft Threat Modeling Fundamentals](https://learn.microsoft.com/en-us/training/paths/tm-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](https://learn.microsoft.com/en-us/training/paths/tm-threat-modeling-fundamentals/) - [STRIDE Framework](https://learn.microsoft.com/en-us/training/modules/tm-use-a-framework-to-identify-threats-and-find-ways-to-reduce-or-eliminate-risk/) - [Threat Modeling Phases](https://learn.microsoft.com/en-us/training/modules/tm-introduction-to-threat-modeling/1b-threat-modeling-phases/) - [Data-Flow Diagram Elements](https://learn.microsoft.com/en-us/training/modules/tm-create-a-threat-model-using-foundational-data-flow-diagram-elements/) - [Prioritise Issues and Apply Security Controls](https://learn.microsoft.com/en-us/training/modules/tm-prioritize-your-issues-and-apply-security-controls/)