Did you know that the employment of Security Development Lifecycle techniques in Microsoft resulted in more secure software? According to surveys the number of security defects reduced by approximately 50 to 60 percent when the team followed SDL. The simple fact is that every product touched by SDL has fewer security defects.
In the article of Michael Howard "A Look Inside the Security Development Lifecycle at Microsoft" it is shown how to solve security problems on the grounds of development phases.
Special thanks to Oliver Szimmetat from Microsoft for the helpful references.