IChannels: Exploiting current management mechanisms to create covert channels in modern processors
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2021
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Conference Paper
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Abstract
To operate efficiently across a wide range of workloads with varying power requirements, a modern processor applies different current management mechanisms, which briefly throttle instruction execution while they adjust voltage and frequency to accommodate for power-hungry instructions (PHIs) in the instruction stream. Doing so 1) reduces the power consumption of non-PHI instructions in typical workloads and 2) optimizes system voltage regulators' cost and area for the common use case while limiting current consumption when executing PHIs.However, these mechanisms may compromise a system's confidentiality guarantees. In particular, we observe that multilevel side-effects of throttling mechanisms, due to PHI-related current management mechanisms, can be detected by two different software contexts (i.e., sender and receiver) running on 1) the same hardware thread, 2) co-located Simultaneous Multi-Threading (SMT) threads, and 3) different physical cores.Based on these new observations on current management mechanisms, we develop a new set of covert channels, IChannels, and demonstrate them in real modern Intel processors (which span more than 70% of the entire client and server processor market). Our analysis shows that IChannels provides more than 24× the channel capacity of state-of-the-art power management covert channels. We propose practical and effective mitigations to each covert channel in IChannels by leveraging the insights we gain through a rigorous characterization of real systems.
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2021 ACM/IEEE 48th Annual International Symposium on Computer Architecture (ISCA)
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985 - 998
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IEEE
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48th Annual International Symposium on Computer Architecture (ISCA 2021)
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Software
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03755 - Capkun, Srdan / Capkun, Srdan
09483 - Mutlu, Onur / Mutlu, Onur