Boosting fuzzer efficiency: an information theoretic perspective

Abstract

In this paper, we take the fundamental perspective of fuzzing as a learning process. Suppose before fuzzing, we know nothing about the behaviors of a program P: What does it do? Executing the first test input, we learn how P behaves for this input. Executing the next input, we either observe the same or discover a new behavior. As such, each execution reveals ”some amount” of information about P’s behaviors. A classic measure of information is Shannon’s entropy. Measuring entropy allows us to quantify how much is learned from each generated test input about the behaviors of the program. Within a probabilistic model of fuzzing, we show how entropy also measures fuzzer efficiency. Specifically, it measures the general rate at which the fuzzer discovers new behaviors. Intuitively, efficient fuzzers maximize information.