Improving Web Application Security: Threats and - CGISecurity

70 Part II: Designing Secure Web ApplicationsThis chapter presents a set of secure architecture and design guidelines. They havebeen organized by common application vulnerability category. These are key areasfor Web application security and they are the areas where mistakes are most oftenmade.How to Use This ChapterThis chapter focuses on the guidelines and principles you should follow whendesigning an application. The following are recommendations on how to use thischapter:● Know the threats to your application so that you can make sure these areaddressed by your design. Read Chapter 2, “Threats and Countermeasures,” togain understanding of the threat types to consider. Chapter 2 lists the threats thatmay harm your application; keep these threats in mind during the design phase.● When designing your application, take a systematic approach to the key areaswhere your application could be vulnerable to attack. Focus on deploymentconsiderations; input validation; authentication and authorization; cryptographyand data sensitivity; configuration, session, and exception management; andadequate auditing and logging to ensure accountability.Architecture and Design Issues for Web ApplicationsWeb applications present designers and developers with many challenges. Thestateless nature of HTTP means that tracking per-user session state becomes theresponsibility of the application. As a precursor to this, the application must be ableto identify the user by using some form of authentication. Given that all subsequentauthorization decisions are based on the user’s identity, it is essential that theauthentication process is secure and that the session handling mechanism used totrack authenticated users is equally well protected. Designing secure authenticationand session management mechanisms are just a couple of the issues facing Webapplication designers and developers. Other challenges occur because input andoutput data passes over public networks. Preventing parameter manipulation andthe disclosure of sensitive data are other top issues.Some of the top issues that must be addressed with secure design practices are shownin Figure 4.1.