Evolution of Defenses against Transient-Execution Attacks

Transient-execution attacks, such as Meltdown and Spectre, exploit performance optimizations in modern CPUs to enable unauthorized access to data across protection boundaries. Against these attacks, we have noticed a rapid growth of deployed and proposed countermeasures. In this paper, we show the evolution of countermeasures against transient-execution attacks by both industry and academia since the initial discoveries of the attacks. We show that despite the advances in the understanding and systematic view of the field, the proposed and deployed defenses are limited.