Threat modeling is a structured way to identify, evaluate, and rank the threats to a system before an attacker does it for you. Teams walk through how a design could be abused, often using a framework like STRIDE to make sure they cover spoofing, tampering, repudiation, information disclosure, denial of service, and elevation of privilege rather than only the risks they happen to think of.
The payoff is a shift from reactive to proactive security. Instead of bolting on controls after a breach, teams design them in while changes are still cheap on a whiteboard. Major software and financial organizations bake threat modeling into their development lifecycle for exactly that reason. The common failure mode is treating it as a one-time document. A model built at design time goes stale the moment the architecture changes, so it needs revisiting whenever the system does.
Why does threat modeling matter for the CISSP exam?
Threat modeling is central to Domain 3: Security Architecture and Engineering and carries into Software Development Security. Know both the general process and the major frameworks used to structure the analysis. NIST describes a data-centric approach in SP 800-154.
Related terms: Attack Surface, Risk Assessment