Security Threat Model

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name: security-threat-model
description: "Write a STRIDE-based threat model for a service or feature. Use when asked to produce a threat model, document security risks, identify attack vectors, assess a service's security posture, or prepare for a security design review. Produces a structured threat model covering assets, trust boundaries, STRIDE threat enumeration per component, risk scores, mitigation controls, and residual risk sign-off."
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# Security Threat Model Skill

Produce a complete STRIDE-based threat model for a service or feature. A threat model is not a list of things that could go wrong — it is a structured analysis of attackers, assets, boundaries, and controls that lets an engineering team make informed, documented security decisions.

A good threat model is specific enough that a new engineer can understand what is being protected, why each control exists, and what risk the team has accepted.

## Required Inputs

Ask for these if not already provided:
- **Service name and description** — what the service does, who uses it
- **Architecture overview** — components, dependencies, data flows (a diagram description or ASCII diagram is fine)
- **Deployment environment** — cloud provider, VPC/network topology, where it runs (Kubernetes, ECS, VMs, serverless)
- **Data sensitivity** — what data does this service handle? PII, payment data, credentials, internal-only?
- **Existing controls** — authentication method, encryption in transit/at rest, current WAF/firewall, existing security scanning
- **Trust levels** — who are the principals? (anonymous public, authenticated users, internal services, admins)

## Output Format

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