CrFuzz: fuzzing multi-purpose programs through input validation

Fuzz testing has been proved its effectiveness in discovering software vulnerabilities. Empowered its randomness nature along with a coverage-guiding feature, fuzzing has been identified a vast number of vulnerabilities in real-world programs. This paper begins with an observation that the design of the current state-of-the-art fuzzers is not well suited for a particular (but yet important) set of software programs. Specifically, current fuzzers have limitations in fuzzing programs serving multiple purposes, where each purpose is controlled by extra options. This paper proposes CrFuzz, which overcomes this limitation. CrFuzz designs a clustering analysis to automatically predict if a newly given input would be accepted or not by a target program. Exploiting this prediction capability, CrFuzz is designed to efficiently explore the programs with multiple purposes. We employed CrFuzz for three state-of-the-art fuzzers, AFL, QSYM, and MOpt, and CrFuzz-augmented versions have shown 19.3% and 5.68% better path and edge coverage on average. More importantly, during two weeks of long-running experiments, CrFuzz discovered 277 previously unknown vulnerabilities where 212 of those are already confirmed and fixed by the respected vendors. We would like to emphasize that many of these vulnerabilities were discoverd from FFMpeg, ImageMagick, and Graphicsmagick, all of which are targets of Google's OSS-Fuzz project and thus heavily fuzzed for last three years by far. Nevertheless, CrFuzz identified a remarkable number of vulnerabilities, demonstrating its effectiveness of vulnerability finding capability.