PHP-sensor: a prototype method to discover workflow violation and XSS vulnerabilities in PHP web applications

As the usage of web applications for security-sensitive facilities has enlarged, the quantity and cleverness of web-based attacks against the web applications have grown-up as well. Several annual cyber security reports revealed that modern web applications suffer from two main categories of attacks: Workflow Violation Attacks and Cross-Site Scripting (XSS) attacks. Presently, in comparison to XSS attacks, there have been actual restricted work carried out that discover workflow violation attacks, as web application logic errors are particular to the expected functionality of a specific web application. This paper presents PHP-Sensor, a novel defensive model that discovers both the vulnerabilities of workflow violation attack and XSS attack concurrently in the real world PHP web applications. For the workflow violation attack, we extract a certain set of axioms by monitoring the sequences of HTTP request/responses and their corresponding session variables during the offline mode. The set of axioms is then utilized for evaluating the HTTP request/response in online mode. Any HTTP request/ response that bypass the corresponding axiom is recognized as a workflow violation attack in PHP web application. For the XSS attack, PHP-Sensor discovers the self-propagating features of XSS worms by monitoring the outgoing HTTP web request with the scripts that are injected in the currently HTTP response web page. We develop prototype of our proposed defensive model on the web proxy as well as on the client-side for the recognition of workflow violation and XSS attacks respectively. We evaluate the detection capability of PHP-Sensor on open source real-world PHP web applications and the simulation outcomes reveal that our defensive model is efficient and feasible at discovering workflow violation attacks, XSS attacks and experiences tolerable performance overhead.