SAND: Decoupling Sanitization from Fuzzing for Low Overhead

Sanitizers provide robust test oracles for various software vulnerabilities. Fuzzing on sanitizer-enabled programs has been the best practice to find software bugs. Since sanitizers need to heavily instrument a target program to insert run-time checks, sanitizer-enabled programs have much higher overhead compared to normally built programs. In this paper, we present SAND, a new fuzzing framework that decouples sanitization from the fuzzing loop. SAND performs fuzzing on a normally built program and only invokes sanitizer-enabled programs when input is shown to be interesting. Since most of the generated inputs are not interesting, i.e., not bug-triggering, SAND allows most of the fuzzing time to be spent on the normally built program. To identify interesting inputs, we introduce execution pattern for a practical execution analysis on the normally built program. We realize SAND on top of AFL++ and evaluate it on 12 real-world programs. Our extensive evaluation highlights its effectiveness: in 24 hours, compared to all the baseline fuzzers, SAND significantly discovers more bugs while not missing any.