Threat Model Initialization

Purpose

Initialize a comprehensive threat model by analyzing your system's architecture documentation. This skill discovers and catalogs:

• Assets: Systems, data stores, services, and integrations
• Data Flows: How data moves between components
• Trust Boundaries: Where privilege levels change
• Attack Surface: Entry points exposed to potential attackers

Usage

/tm-init [--docs <path>] [--scope <pattern>] [--framework stride|pasta]

Arguments (parsed from $ARGUMENTS):

• --docs <path>: Path to architecture documentation (default: ./docs)
• --scope <pattern>: Limit analysis to matching components
• --framework: Threat framework to use (default: stride)

Process

Step 1: Discover Documentation

Scan the documentation directory for architecture artifacts:

Glob patterns to search:
- **/*.md (Markdown documentation)
- **/README* (Project readmes)
- **/openapi.yaml, **/openapi.json (API specs)
- **/swagger.* (Swagger specs)
- **/*.mmd, **/*.puml (Diagrams)
- **/docker-compose.* (Infrastructure)
- **/Dockerfile* (Containerization)
- **/*.tf (Terraform)
- **/k8s/**, **/kubernetes/** (Kubernetes)

Step 2: Extract Assets

For each component found, identify and classify:

Asset Types:

Data Classifications:

• public: Publicly available information
• internal: Internal business data
• confidential: Sensitive business data
• restricted: PII, PHI, financial data, credentials

Step 3: Map Data Flows

Identify how data moves between components:

• Source and destination assets
• Data types being transmitted
• Protocol (HTTP, HTTPS, gRPC, WebSocket, etc.)
• Authentication method
• Encryption status
• Whether it crosses a trust boundary

Step 4: Define Trust Boundaries

Identify where security context changes:

Trust Boundary Types:

• network: Public/DMZ/Internal network segmentation
• process: Process/container isolation
• privilege: User/admin/system privilege changes
• environment: Dev/staging/prod boundaries
• organizational: Third-party/vendor boundaries
• data-classification: Sensitivity level changes

Step 5: Catalog Attack Surface

Document all entry points:

Attack Surface Types:

• api: REST, GraphQL, gRPC endpoints
• web-ui: Web application interfaces
• mobile: Mobile application entry points
• cli: Command-line interfaces
• admin: Administrative interfaces
• integration: Webhooks, callbacks
• file-upload: File upload functionality
• message-queue: Message queue consumers

Step 6: Generate Diagrams

Create Mermaid diagrams for visualization.

Output Structure

Create the following directory structure:

.threatmodel/
├── config.yaml
├── state/
│   ├── assets.json
│   ├── dataflows.json
│   ├── trust-boundaries.json
│   ├── attack-surface.json
│   └── sequences.json
├── diagrams/
│   ├── architecture.mmd
│   ├── dataflow.mmd
│   └── trust-boundaries.mmd
├── reports/
├── baseline/
└── policies/

Config File Template

Create .threatmodel/config.yaml:

project:
  name: "[Project Name]"
  version: "1.0.0"
  description: "[Description]"

analysis:
  framework: "stride"
  depth: "standard"

documentation:
  paths:
    - "./docs"
  patterns:
    - "**/*.md"
    - "**/openapi.yaml"

verification:
  code_paths:
    - "./src"
  exclude_paths:
    - "./node_modules"
    - "./**/*.test.*"

compliance:
  frameworks:
    - owasp

JSON Output Format

assets.json

{
  "version": "1.0",
  "generated": "ISO-8601 timestamp",
  "assets": [
    {
      "id": "asset-001",
      "name": "User Database",
      "type": "data-store",
      "classification": "restricted",
      "description": "PostgreSQL database storing user data",
      "owner": "platform-team",
      "data_types": ["pii", "credentials"],
      "code_references": ["src/db/connection.ts"]
    }
  ]
}

dataflows.json

{
  "version": "1.0",
  "generated": "ISO-8601 timestamp",
  "dataflows": [
    {
      "id": "flow-001",
      "name": "User Login",
      "source": {"asset_id": "asset-001", "component": "LoginPage"},
      "destination": {"asset_id": "asset-002", "component": "AuthService"},
      "data_types": ["credentials"],
      "protocol": "HTTPS",
      "encryption": {"in_transit": true},
      "crosses_trust_boundary": true,
      "trust_boundary_id": "tb-001"
    }
  ]
}

Instructions for Claude

When executing this skill:

1. Ask for documentation path if not provided in arguments

2. Explore the documentation:

   • Use Glob to find all relevant files
   • Read architecture docs, README files, API specs
   • Look for existing diagrams or system descriptions

3. Build understanding of the system:

   • List all named components
   • Understand how they connect
   • Note external dependencies
   • Identify where data enters/exits

4. Create the threat model structure:

   • Create .threatmodel/ directory
   • Write config.yaml with project info
   • Write each state file with discovered data
   • Generate Mermaid diagrams

5. Validate completeness:

   • Every asset should have at least one data flow
   • Every external-facing component should be in attack surface
   • Trust boundaries should be identified

6. Write visual discovery report (.threatmodel/reports/discovery-report.md):

   # Discovery Report
   
   **Project**: [Name]
   **Generated**: [Date]
   
   ## System Overview
   
   

   DISCOVERY SUMMARY ═══════════════════════════════════════════════════════════

   ASSETS DISCOVERED: 14 ───────────────────────────────────────────────────────── Services │████████████████░░░░░░░░░░░░░░░░░░░░░░░░│ 4 Data Stores │████████████░░░░░░░░░░░░░░░░░░░░░░░░░░░░│ 3 Clients │████████░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░│ 2 Integrations │████████████████████░░░░░░░░░░░░░░░░░░░░│ 5

   DATA FLOWS: 22 (8 cross trust boundaries) TRUST BOUNDARIES: 5 ATTACK SURFACE ENTRIES: 12

   
   ## Assets by Classification
   
   | Asset | Type | Classification |
   |-------|------|----------------|
   | User Database | data-store | Restricted |
   | API Gateway | service | Internal |
   ...
   

7. Console summary (also display to user):

   Threat Model Initialized
   ========================
   
   Project: [Name]
   Framework: STRIDE
   
   Discovered:
     - X assets (breakdown by type)
     - Y data flows (Z cross trust boundaries)
     - N trust boundaries
     - M attack surface entries
   
   Created:
     .threatmodel/config.yaml
     .threatmodel/state/assets.json
     .threatmodel/state/dataflows.json
     .threatmodel/state/trust-boundaries.json
     .threatmodel/state/attack-surface.json
     .threatmodel/reports/discovery-report.md
     .threatmodel/diagrams/architecture.mmd
     .threatmodel/diagrams/dataflow.mmd
   
   Next Steps:
     Run /tm-threats to analyze threats
   

Reference Files

• STRIDE Framework
• Data Schema