Improving Web Application Security: Threats and - CGISecurity

100 Part II:Designing Secure Web ApplicationsHow to Use This ChapterThis chapter gives you the questions to ask when performing a thorough review ofyour architecture design. The following are recommendations on how to use thischapter:● Integrate a security review into your architecture design process. Start early on,and as your design changes, review those changes with the steps given in thischapter.● Evolve your security review. This chapter provides questions that you can ask toimprove the security of your design. To complete the review process, you mightalso need to add specific questions that are unique to your application.● Know the threats you are reviewing against. Chapter 2, “Threats andCountermeasures,” lists the threats that affect the various components and layersthat make up your application. Knowing these threats is essential to improving theresults of your review process.Architecture and Design Review ProcessThe architecture and design review process analyzes the architecture and design froma security perspective. If you have just completed the design, the designdocumentation can help you with this process. Regardless of how comprehensiveyour design documentation is, you must be able to decompose your application andbe able to identify key items, including trust boundaries, data flow, entry points, andprivileged code. You must also know the physical deployment configuration of yourapplication. Pay attention to the design approaches you have adopted for those areasthat most commonly exhibit vulnerabilities. This guide refers to these as applicationvulnerability categories.Consider the following aspects when you review the architecture and design of yourapplication:● Deployment and infrastructure. You review the design of your application inrelation to the target deployment environment and the associated security policies.You also consider the restrictions imposed by the underlying infrastructure-layersecurity.● Application architecture and design. You review the approach to critical areas inyour application, including authentication, authorization, input validation,exception management, and other areas. You can use the application vulnerabilitycategories as a roadmap and to ensure that you do not miss any key areas duringthe review.● Tier-by-tier analysis. You walk through the logical tiers of your application andexamine the security of ASP.NET Web pages and controls, Web services, servicedcomponents, Microsoft .NET Remoting, data access code, and others.