Finding Bugs in Dynamic Web Applications

Web script crashes and malformed dynamically-generated web pages are common errors, and they seriously impact usability of web applications. Current tools for web-page validation cannot handle the dynamically-generated pages that are ubiquitous on today’s Internet. In this work, we apply a dynamic test generation technique, based on combined concrete and symbolic execution, to the domain of dynamic web applications. The technique generates tests automatically and minimizes the bug-inducing inputs to reduce duplication and to make the bug reports small and easy to understand and fix. We implemented the technique in Apollo, an automated tool that found dozens of bugs in real PHP applications. Apollo generates test inputs for the web application, monitors the application for crashes, and validates that the output conforms to the HTML specification. This paper presents Apollo’s algorithms and implementation, and an experimental evaluation that revealed a total of 214 bugs in 4 open-source PHP web applications.

By: Shay Artzi; Adam Kiezun; Julian Dolby; Frank Tip; Danny Dig; Amit Paradkar; Michael D. Ernst

Published in: RC24528 in 2008


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