FuzzCache: Optimizing Web Application Fuzzing Through Software-Based Data Cache

Fuzzing has shown great promise in detecting vulnerabilities in server-side web applications. In this work, we introduce an innovative software-based data cache mechanism that complements and improves all existing web application fuzzing tools. Our key observation is that a great proportion of execution time (e.g., 50%) of web applications is spent on fetching data from two major sources: database and network; our in-depth investigation reveals that the same data is often repeatedly fetched across fuzzing trials. We thus design a new solution, FuzzCache, that stores the data into softwarebased caches, mitigating the need for repeated and expensive data fetches. FuzzCache exposes the cached data across fuzzing trials through inter-process shared memory segments. It also, as the first work, incorporates just-in-time compilation to avoid the performance overhead associated with interpreting PHP code in real time, thereby enhancing execution efficiency.

We demonstrate that FuzzCache significantly enhances web application fuzzing performance. In our experiments, we integrated FuzzCache with both a black-box fuzzer (Black-Widow) and a greybox fuzzer (WebFuzz). The results illustrate that FuzzCache accelerates both black-box and grey-box fuzzing, achieving a throughput increase of 3× to 4×. FuzzCache substantially improves code coverage by an average of 25%. Consequently, FuzzCache enables faster vulnerability detection, leading to the discovery of a greater number of vulnerabilities.