A Survey of Microarchitectural Covert-Channel Attacks, Defenses and Detection.

Covert channels based on processor microarchitecture have become a major threat to modern processors by bypassing existing security detection to transmit or leak secrets. Based on the storage time of covert channels, this paper divides microarchitecture-based covert channels into two types: persistent covert channels and volatile covert channels. The principle of the attack, runtime characteristics, typical attacks and attack conditions of the two types of covert channels are introduced and the existing covert channels are evaluated by the existing metrics. Based on the analysis of the attack conditions, a new analysis method on how to find the potential covert channel in microprocessor resources is proposed, and the microprocessor resources that are not used by existing covert channels are analyzed. The analysis shows that, the front-end bus in the Intel processors meets the conditions for creating a new transient covert channel. Based on the working principle of microarchitecture-based covert channel, many strategies of protection and detection methods have been proposed, and they are classified according to the working principles. The working principle, existing strategies and application scope of each type are introduced in detail. Moreover, reasonable and feasible protection suggestions are proposed for potential microarchitecture-based covert channels that may exist in the future. [ABSTRACT FROM AUTHOR]