A Covert Channel Using Core Alternation

The improvement in performance gained by the use of multi-core processors led to security problem. In this paper, we present a new covert channel which we called the "core-alternative channel". This covert channel could exist in most operating systems and virtualization platforms with multi-core processors. We have developed CCCA (Covert Channels using Core-alternation), a prototype that creates a core-alternative channel and communicates data secretly. We discuss how to mitigate and eliminate this channel. We quantitatively evaluate the threat of core-alternative channel both between processes on Linux and between virtual machines on the Xen hyper visor. We also measured the bandwidth and communication accuracy of this covert channel.