Towards a structured unified process for software security.

Security is often an afterthought when developing software, and is often bolted on late in development or even during deployment or maintenance, through activities such as penetration testing, add-on security software and penetrate-and patch maintenance. We believe that security needs to be built in to the software from the beginning, and that security activities need to take place throughout the software lifecycle. Accomplishing this effectively and efficiently requires structured approach combining a detailed understanding on what causes vulnerabilities, and how specific activities combine to prevent them.In this paper we introduce key elements of the approach we are taking: vulnerability cause graphs, which encode information about vulnerability causes, and security activity graphs, which encode information about security activities. We discuss how these can be applied to design software development processes (or changes to processes) that eliminate software vulnerabilities.