FMViz: Visualizing Tests Generated by AFL at the Byte-level
This tool helps developers and students better understand AFL fuzzer inner-workings, but it is incremental as it extends an existing fuzzer with visualization features.
The paper tackles the difficulty of monitoring and understanding fuzzer behavior due to its randomness by developing FMViz, a tool that visualizes byte-level mutations in AFL-generated test inputs, highlighting changes between seeds to aid comprehension.
Software fuzzing is a strong testing technique that has become the de facto approach for automated software testing and software vulnerability detection in the industry. The random nature of fuzzing makes monitoring and understanding the behavior of fuzzers difficult. In this paper, we report the development of Fuzzer Mutation Visualizer (FMViz), a tool that focuses on visualizing byte-level mutations in fuzzers. In particular, FMViz extends American Fuzzy Lop (AFL) to visualize the generated test inputs and highlight changes between consecutively generated seeds as a fuzzing campaign progresses. The overarching goal of our tool is to help developers and students comprehend the inner-workings of the AFL fuzzer better. In this paper, we present the architecture of FMViz, discuss a sample case study of it, and outline the future work. FMViz is open-source and publicly available at https://github.com/AftabHussain/afl-test-viz.