SymFusion: Hybrid Instrumentation for Concolic Execution

Concolic execution is a dynamic twist of symbolic execution designed with scalability in mind. Recent concolic executors heavily rely on program instrumentation to achieve such scalability. The instrumentation code can be added at compilation time (e.g., using an LLVM pass), or directly at execution time with the help of a dynamic binary translator. The former approach results in more efficient code but requires recompilation. Unfortunately, recompiling the entire code of a program is not always feasible or practical (e.g., in presence of third-party components). On the contrary, the latter approach does not require recompilation but incurs significantly higher execution time overhead. In this paper, we investigate a hybrid instrumentation approach for concolic execution, called SymFusion. In particular, this hybrid instrumentation approach allows the user to recompile the core components of an application, thus minimizing the analysis overhead on them, while still being able to dynamically instrument the rest of the application components at execution time. Our experimental evaluation shows that our design can achieve a nice balance between efficiency and efficacy on several real-world applications.