We present CacheOut, a new speculative execution attack that is capable of leaking data from Intel CPUs across many security boundaries. We show that despite Intel's attempts to address previous generations of speculative execution attacks, CPUs are still vulnerable, allowing attackers to exploit these vulnerabilities to leak sensitive data.
Moreover, unlike previous MDS issues, we show in our work how an attacker can exploit the CPU's caching mechanisms to select what data to leak, as opposed to waiting for the data to be available. Finally, we empirically demonstrate that CacheOut can violate nearly every hardware-based security domain, leaking data from the OS kernel, co-resident virtual machines, and even SGX enclaves.
We would like to thank Intel for working with us during the responsible disclosure.
This research was supported by the Defense Advanced Research Projects Agency (DARPA) and Air Force Research Laboratory (AFRL) under contract FA8750-19-C0531, by an Australian Research Council Discovery Early Career Researcher Award (project number DE200101577), and by generous gifts from Intel and AMD.