Modeling

Threat modeling in TTModeler Pro follows a structured methodology to systematically identify, assess, and mitigate security risks in your system. The process guides you from initial system characterization through validation and documentation, ensuring comprehensive coverage of potential threats across hardware, software, and operational contexts.

Table of Contents

• System Overview
• Assets
• Diagrams
• Threats and Mitigations
• Risk Assessment
• Checklists
• Test Cases

The Thing Threat Modeling (TTM) Process

The thing threat modeling workflow consists of 13 steps:

1. System Characterization & Scope Definition - Define system characteristics, requirements, and scope boundaries
2. Business Objectives and Impact Definition - Define goals and identify potential business impacts
3. System Interaction Analysis - Identify actors, external systems, use cases, and privileges
4. Asset Identification - Identify and classify all valuable assets
5. Threat and Threat Source Identification - Identify threat sources, their motives, and threats against the system
6. Hardware Threat Modeling - Create hardware models and identify attack scenarios
7. Software Threat Modeling - List software components and identify attack scenarios
8. Use Case Threat Modeling - Create DFDs for use cases and identify attack scenarios
9. Process Threat Modeling - Identify security-relevant processes and analyze gaps
10. Vulnerability Review & Penetration Testing - Check against vulnerability databases and conduct penetration tests
11. Risk Assessment - Assess severity and likelihood to determine risk levels
12. Countermeasure Definition - Define mitigations and calculate residual risk
13. Validation & Documentation - Validate countermeasures, verify the model, and document and communicate results

Modeling Sections

System Overview

Define your system's characteristics, scope, and boundaries. Characterize the sector, function, requirements, criticality, and environment. Identify stakeholders, regulatory requirements, and business objectives that drive your security posture.

Assets

Identify and classify all valuable assets in your system. Document data assets using classification standards (NIST SP 800-53, ISO 27001, GDPR), considering all actors and their interactions with sensitive information.

Diagrams

Create visual models of your system including context diagrams, use case diagrams, data flow diagrams (DFDs), and hardware/software architecture models. These diagrams help identify attack surfaces and potential threat vectors across different system layers.

Threats and Mitigations

Identify threat sources (adversarial and non-adversarial), define threats against your assets, and analyze attack scenarios across hardware, software, use cases, and processes. Define countermeasures to mitigate, avoid, or transfer identified risks.

Risk Assessment

Assess all identified attack vectors and weaknesses using severity and likelihood scores. Calculate risk levels and prioritize threats that exceed tolerable thresholds. Determine residual risk after countermeasures are applied.

Checklists

Conduct compliance checks against regulatory and industry requirement lists such as IEC 62443-4-2 or EU CRA Annex I. Use checklists to verify that your system meets security requirements and to identify gaps in compliance coverage.

Test Cases

Develop test cases to validate the effectiveness of implemented countermeasures. Document assumptions, conduct penetration testing, and verify that the system model accurately reflects reality.