Introduction
Incorporating security at the design phase of software development can prevent many vulnerabilities before they are coded. Threat modeling is a structured approach that identifies, prioritizes, and mitigates potential security risks in an application’s architecture. When applied early in the SDLC, it provides actionable insights to developers, architects, and security teams, improving both software design and security posture.

What Is Threat Modeling?
Threat modeling is the process of analyzing a system’s architecture to identify potential attack vectors, security flaws, and countermeasures. It helps teams answer essential questions: What are we building? What can go wrong? What are we doing about it?

Common Methodologies

1. STRIDE (Spoofing, Tampering, Repudiation, Information Disclosure, Denial of Service, Elevation of Privilege) – Categorizes threats based on attacker goals.
2. DREAD (Damage, Reproducibility, Exploitability, Affected Users, Discoverability) – Used to assess the severity of identified threats.
3. PASTA (Process for Attack Simulation and Threat Analysis) – Focuses on attacker behavior and business impact.

When and How to Apply Threat Modeling
The ideal time to perform threat modeling is during the design or planning phase. However, it can also be conducted during major updates or architectural changes. Steps typically include:

• Define the application’s scope and assets.
• Diagram data flows and components.
• Identify threats using a chosen model.
• Prioritize risks based on impact and likelihood.
• Define mitigation strategies and document outcomes.

Benefits of Early Threat Modeling
By identifying flaws early, organizations can prevent costly security rework and reduce time-to-market. It also improves communication between developers and security teams, aligning everyone on shared security goals. Most importantly, it fosters a proactive, rather than reactive, security culture.

Conclusion
Threat modeling is a cornerstone of secure software design. By incorporating it into the early stages of the SDLC, organizations can prevent vulnerabilities before they are introduced, reduce costs, and increase software reliability and trustworthiness.