FUZZUER: Enabling Fuzzing of UEFI Interfaces on EDK-2

Unified Extensible Firmware Interface (UEFI) specification describes a platform-independent pre-boot interface for an Operating System (OS).EDK-2 Vulnerabilities in UEFI interface functions have severe consequences and can lead to Bootkits and other persistent malware resilient to OS reinstallations.However, there exist no vulnerability detection techniques for UEFI interfaces.We present FUZZUER, a feedback-guided fuzzing technique for UEFI interfaces on EDK-2, an exemplary and prevalently used UEFI implementation.We designed FIRNESS that utilizes static analysis techniques to automatically generate fuzzing harnesses for interface functions.We evaluated FUZZUER on the latest version of EDK-2.Our comprehensive evaluation on 150 interface functions demonstrates that FUZZUER with FIR-NESS is an effective testing technique of EDK-2's UEFI interface functions, greatly outperforming HBFA, an existing testing tool with manually written harnesses.We found 20 new security vulnerabilities, and most of these are already acknowledged by the developers.