Introduction

Computer security people tend to fall into one of two camps on design review. People from a formal development background are usually receptive to the design review process. This is only natural, as it maps closely to most formal software development methodologies. The design review process can also seem to be less trouble than reviewing a large application code base manually.

In the other camp are code auditors who delight in finding the most obscure and complex vulnerabilities. This crowd tends to look at design review as an ivory-tower construct that just gets in the way of the real work. Design review's formalized process and focus on documentation come across as a barrier to digging into the code.

The truth is that design review falls somewhere between the views of these two camps, and it has value for both. Design review is a useful tool for identifying vulnerabilities in application architecture and prioritizing components for implementation review. It doesn't replace implementation review, however; it's just a component of the complete review process. It makes identifying design flaws a lot easier and provides a more thorough analysis of the security of a software design. In this capacity, it can make the entire review process more effective and ensure the best return for the time you invest.

This chapter gives you some background on the elements of software design and design vulnerabilities, and introduces a review process to help you identify security concerns in a software design.