Threat Modeling

Identify, prioritize, and mitigate security threats systematically using STRIDE methodology

Level 1: Quick Reference

STRIDE Threat Categories

threats:
  S_spoofing:
    description: Impersonating something or someone else
    targets: [authentication, identity]
    example: "Using stolen credentials to access system"

  T_tampering:
    description: Modifying data or code maliciously
    targets: [data_integrity, code_integrity]
    example: "Altering transaction amounts in transit"

  R_repudiation:
    description: Claiming to not have performed an action
    targets: [logging, audit_trails]
    example: "Denying fraudulent transaction was performed"

  I_information_disclosure:
    description: Exposing information to unauthorized parties
    targets: [confidentiality, data_protection]
    example: "Leaking customer PII through error messages"

  D_denial_of_service:
    description: Making system unavailable or degraded
    targets: [availability, performance]
    example: "Overwhelming API with requests"

  E_elevation_of_privilege:
    description: Gaining unauthorized higher access level
    targets: [authorization, access_control]
    example: "Exploiting bug to gain admin rights"

Four Key Questions

1. What are we building?

   • System architecture, components, data flows
   • Trust boundaries, entry/exit points

2. What can go wrong?

   • Apply STRIDE to each component
   • Identify threat scenarios

3. What should we do about it?

   • Prioritize threats (DREAD scoring)
   • Design mitigations

4. Did we do a good job?

   • Review threat model coverage
   • Validate mitigations

Essential Checklist

Planning Phase:

• Identify system scope and boundaries
• Document assets and data flows
• Define security objectives
• Assemble threat modeling team

Analysis Phase:

• Create data flow diagrams (DFD)
• Mark trust boundaries
• Apply STRIDE to each element
• Document threat scenarios
• Build attack trees

Prioritization:

• Score threats using DREAD
• Classify by impact and likelihood
• Map to security controls (NIST RA-3)

Mitigation:

• Design countermeasures
• Assign ownership and timeline
• Track implementation status
• Verify effectiveness (NIST RA-5)

Documentation:

• Maintain threat model repository
• Update for architecture changes
• Share findings with stakeholders
• Schedule periodic reviews

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Level 2:

📚 Full Examples: See REFERENCE.md for complete code samples, detailed configurations, and production-ready implementations.

Implementation Guide

STRIDE Methodology

Systematic Threat Identification

See REFERENCE.md for complete implementation.

STRIDE-per-Element Pattern

See REFERENCE.md for complete implementation.

Attack Trees

Building Attack Trees

See REFERENCE.md for complete implementation.

Attack Tree Template

See REFERENCE.md for complete implementation.

Data Flow Diagrams (DFD)

DFD Notation

See REFERENCE.md for complete implementation.

Example DFD: Web Application

See REFERENCE.md for complete implementation.

DFD Analysis Checklist

See REFERENCE.md for complete implementation.

Trust Boundaries

Identifying Trust Boundaries

See REFERENCE.md for complete implementation.

Boundary Crossing Analysis

See REFERENCE.md for complete implementation.

Threat Prioritization (DREAD)

DREAD Scoring System

See REFERENCE.md for complete implementation.

Threat Prioritization Example

See REFERENCE.md for complete implementation.

Mitigation Strategies

Mitigation Pattern Catalog

See REFERENCE.md for complete implementation.

PASTA Methodology

Process for Attack Simulation and Threat Analysis

See REFERENCE.md for complete implementation.

Tools

Microsoft Threat Modeling Tool

See REFERENCE.md for complete implementation.

Threat Modeling Workflow

See REFERENCE.md for complete implementation.

NIST Integration

NIST RA-3: Risk Assessment

See REFERENCE.md for complete implementation.

NIST RA-5: Vulnerability Monitoring and Scanning

See REFERENCE.md for complete implementation.

Practical Examples

Example 1: Authentication Service Threat Model

See REFERENCE.md for complete implementation.

Example 2: API Gateway Threat Model

See REFERENCE.md for complete implementation.

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Level 3: Deep Dive Resources

Advanced Topics

• Threat Intelligence Integration: MITRE ATT&CK mapping, threat feeds
• Automated Threat Modeling: CI/CD integration, continuous threat modeling
• Threat Model Maintenance: Version control, change management
• Quantitative Risk Analysis: Monte Carlo simulations, risk metrics
• Threat Modeling at Scale: Enterprise architecture, microservices
• Supply Chain Threat Modeling: Third-party components, dependencies

Tools & Frameworks

• Commercial: IriusRisk, ThreatModeler, SD Elements
• Open Source: OWASP Threat Dragon, PyTM, Threagile
• Cloud-Native: AWS Threat Composer, Azure Threat Modeling
• Standards: NIST SP 800-30 (Risk Assessment), ISO 27005

References

• OWASP Threat Modeling: https://owasp.org/www-community/Threat_Modeling
• Microsoft SDL: https://www.microsoft.com/en-us/securityengineering/sdl/threatmodeling
• NIST SP 800-30 Rev 1: Risk Assessment Guide
• NIST SP 800-154: Data Integrity Guide
• Adam Shostack's "Threat Modeling" Book: Industry standard reference
• MITRE ATT&CK: https://attack.mitre.org

Community

• OWASP Threat Modeling Project: Resources, templates, guidance
• Threat Modeling Slack: Community discussions
• Security BSides: Local threat modeling workshops

Examples

Basic Usage

// TODO: Add basic example for threat-modeling
// This example demonstrates core functionality

Advanced Usage

// TODO: Add advanced example for threat-modeling
// This example shows production-ready patterns

Integration Example

// TODO: Add integration example showing how threat-modeling
// works with other systems and services

See examples/threat-modeling/ for complete working examples.

Integration Points

This skill integrates with:

Upstream Dependencies

• Tools: Common development tools and frameworks
• Prerequisites: Basic understanding of general concepts

Downstream Consumers

• Applications: Production systems requiring threat-modeling functionality
• CI/CD Pipelines: Automated testing and deployment workflows
• Monitoring Systems: Observability and logging platforms

Related Skills

• See other skills in this category

Common Integration Patterns

1. Development Workflow: How this skill fits into daily development
2. Production Deployment: Integration with production systems
3. Monitoring & Alerting: Observability integration points

Common Pitfalls

Pitfall 1: Insufficient Testing

Problem: Not testing edge cases and error conditions leads to production bugs

Solution: Implement comprehensive test coverage including:

• Happy path scenarios
• Error handling and edge cases
• Integration points with external systems

Prevention: Enforce minimum code coverage (80%+) in CI/CD pipeline

Pitfall 2: Hardcoded Configuration

Problem: Hardcoding values makes applications inflexible and environment-dependent

Solution: Use environment variables and configuration management:

• Separate config from code
• Use environment-specific configuration files
• Never commit secrets to version control

Prevention: Use tools like dotenv, config validators, and secret scanners

Pitfall 3: Ignoring Security Best Practices

Problem: Security vulnerabilities from not following established security patterns

Solution: Follow security guidelines:

• Input validation and sanitization
• Proper authentication and authorization
• Encrypted data transmission (TLS/SSL)
• Regular security audits and updates

Prevention: Use security linters, SAST tools, and regular dependency updates

Best Practices:

• Follow established patterns and conventions for threat-modeling
• Keep dependencies up to date and scan for vulnerabilities
• Write comprehensive documentation and inline comments
• Use linting and formatting tools consistently
• Implement proper error handling and logging
• Regular code reviews and pair programming
• Monitor production metrics and set up alerts

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Next Steps:

1. Review bundled templates in templates/
2. Use stride-template.md for your first threat model
3. Generate DFDs with data-flow-diagram.md
4. Run threat-report-generator.py to create reports
5. Study real-world examples in resources/stride-examples.md

Related Skills: [security-testing] [secure-coding] [vulnerability-management]