Adversarial Assertions

Assertions are statements that can be embedded inside any software program or hardware implementation for checking expected behaviors. They are widely used for validation of functional behaviors as well as faster bug localization. There are no prior efforts to investigate whether the assertions can be exploited by an adversary. In this paper, we demonstrate a timing side-channel attack by exploiting the assertion behaviors. Specifically, we show that an adversary can get unauthorized data by exploiting branch prediction methodologies as well as exception handling delay in assertions. Experimental results demonstrate that our attack is successful on multiple Intel and AMD processors. State-of-the-art Spectre fuzzing tools are unable to detect the attack from adversarial assertions. Therefore, the designers should consider the security implications before introducing assertions in their designs. We also propose a mitigation technique to defend against adversarial assertions.