Fuzz to the Future: Uncovering Occluded Future Vulnerabilities via Robust Fuzzing

The security landscape of software systems has witnessed considerable advancements through dynamic testing methodologies, especially fuzzing. Traditionally, fuzzing involves a sequential, cyclic process where software is tested to identify crashes. These crashes are then triaged and patched, leading to subsequent cycles that uncover further vulnerabilities. While effective, this method is not efficient as each cycle potentially reveals new issues previously obscured by earlier crashes, thus resulting in vulnerabilities being discovered sequentially. In this paper, we present a solution to identify occluded future vulnerabilities — vulnerabilities that are hard or impossible to trigger due to current vulnerabilities occluding the triggering path. We introduce robust fuzzing, a novel technique that enables fuzzers probe beyond the immediate crash location and uncover new vulnerabilities or variants of known ones. We implemented robust fuzzing in FlakJack, a pioneering fuzzing add-on that leverages binary patching to proactively identify occluded future vulnerabilities hidden behind current crashes. By enabling fuzzers to bypass immediate crash points and delve deeper into the software, FlakJack not only accelerates the vulnerability discovery process but also significantly enhances the efficacy of software testing. With the help of FlakJack, we found 28 new vulnerabilities in projects that have been extensively tested through the OSS-Fuzz project. This approach promises a transformative shift in how vulnerabilities are identified and managed, aiming to shorten the time span of vulnerability discovery over the long term.