EvilCS: An Evaluation of Information Leakage through Context Switching on Security Enclaves

Security enclaves provide isolated execution environments for trusted applications. However, modern processors utilize diverse performance enhancement methods (e.g., branch prediction and parallel execution) that can introduce security vulnerabilities. Specifically, if a processor leaks any information, an adversary can monitor and recover secrets from trusted applications. This paper makes a connection between context switching and information leakage in security enclaves. We present an evaluation framework that analyzes the potential channels through which context switching can expose sensitive information across the security enclave boundaries as a physical side-channel signature. Specifically, we propose a statistical information leakage assessment technique to evaluate the side-channel leakage of a security enclave during the pre-silicon design stage. Experimental evaluation on multiple RISC-V security enclaves reveals that context switching introduces power side channels that an adversary can exploit to infer the execution sequences as well as register values of trusted applications.