Comparing Countermeasures against Interrupt-Related Covert Channels in an Information-Theoretic Framework

Interrupt-driven communication with hardware devices can be exploited for establishing covert channels. In this article, we propose an information-theoretic framework for analyzing the bandwidth of such interrupt-related channels while taking aspects of noise into account. As countermeasures, we present mechanisms that are already implemented in some operating systems, though for a different purpose. Based on our formal framework, the effectiveness of the mechanisms is evaluated. Despite the large body of work on covert channels, this is the first comprehensive account of interrupt-related covert channel analysis and mitigation.