Secure Design

Secure design is where you decide how a system will resist attack, then document those risks and controls so they can be tracked and checked.

Key concepts

• Threat modeling asks a simple question early: what could go wrong here? Sketch the data flows and name the likely abuses. You do not need a formal method to start.
• Pair every identified risk with a specific control and a named owner. A risk with neither is just a note in a file. Tracking makes the list something you can review.
• Design layered defenses so that no single control failure exposes the whole system. This is what defense in depth means in practice, and it assumes some control will eventually fail.
• Keep the design simple and make it fail closed. Complexity hides flaws, and a confused system usually fails open. Simple designs are also far easier to review.
• Include third-party components and services in the design review. Their weaknesses become yours the moment you ship. Decide what each dependency is trusted to do.

Why it matters for your business

Fixing a design flaw on paper costs a fraction of fixing that same flaw once it is running in production. Documented risks and controls also make audits and customer security questionnaires far less painful. The same discipline belongs on software you buy rather than build, which is what vendor risk management extends to your suppliers.