S$w$Fuzz: Structure-Sensitive WebAssembly Fuzzing

WebAssembly (WASM) has rapidly emerged as a ubiquitous target for web browsers, server-side applications, and blockchain platforms, with promising performance and portability. As WASM grows in popularity, ensuring its security and resilience becomes paramount. However, traditional fuzzing approaches struggle to detect potential security vulnerabilities in existing WebAssembly runtimes due to their lack of perception of the WASM file structure. In this paper, we introduce Sw Fuzz, a dedicated fuzzing framework tailored for WASM binaries. SwFuzz integrates comprehensive structure-sensitive policies that capture the nuances and intricacies within the WASM binaries. Our proposed fuzzing framework not only identifies vulnerabilities present in conventional binaries but also emphasizes the detection of WASM-specific bugs that have previously gone unnoticed. Experimental results demonstrate that Sw Fuzz has discovered numerous new bugs, with 17 CCVEs being assigned, underscoring the importance of a specialized fuzzing framework for evolving platforms like WASM. Our findings also highlight the critical requirement for a proactive approach to securing the WASM landscape.