A Novel Covert Channel Attack Using Memory Encryption Engine Cache

Microarchitectural covert channel attack is a threat when multiple tenants share hardware resources such as last-level cache. In this work, we propose a novel covert channel attack that exploits new microarchitecture that have been introduced to support memory encryption - in particular, the memory encryption engine (MEE) cache. The MEE cache is a shared resource but only utilized when accessing the integrity tree data and provides opportunity for a stealthy covert channel attack. However, there are challenges since MEE cache organization is not publicly known and the access behavior differs from a conventional cache. We demonstrate how the MEE cache can be exploited to establish a covert channel communication.