Semi-Automatic Security Testing of Web Applications from a Secure Model

Web applications are a major target of attackers. The increasing complexity of such applications and the subtlety of today's attacks make it very hard for developers to manually secure their web applications. Penetration testing is considered an art, the success of a penetration tester in detecting vulnerabilities mainly depends on his skills. Recently, model-checkers dedicated to security analysis have proved their ability to identify complex attacks on web-based security protocols. However, bridging the gap between an abstract attack trace output by a model-checker and a penetration test on the real web application is still an open issue. We present here a methodology for testing web applications starting from a secure model. First, we mutate the model to introduce specific vulnerabilities present in web applications. Then, a model-checker outputs attack traces that exploit those vulnerabilities. Next, the attack traces are translated into concrete test cases by using a 2-step mapping. Finally, the tests are executed on the real system using an automatic procedure that may request the help of a test expert from time to time. A prototype has been implemented and evaluated on Web Goat, an insecure web application maintained by OWASP. It successfully reproduced Role-Based Access Control (RBAC) and Cross-Site Scripting (XSS) attacks.