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Shared memory system-on-chips (SM-SoCs) are ubiquitously employed by a wide range of computing platforms, including edge/IoT devices, autonomous systems, and smartphones. In SM-SoCs, system-wide shared memory enables a convenient and cost-effective mechanism for making data accessible across dozens of processing units (PUs), such as CPU cores and domain-specific accelerators. Due to the diverse computational characteristics of the PUs they embed, SM-SoCs often do not employ a shared last-level cache (LLC). Although covert channel attacks have been widely studied in shared memory systems, high-throughput communication has previously been feasible only by relying on an LLC or by possessing privileged or physical access to the shared memory subsystem. In this study, we introduce a new memory-contention-based covert communication attack, MC3, which specifically targets shared system memory in mobile SoCs. Unlike existing attacks, our approach achieves high-throughput communication without the need for an LLC or elevated access to the system. We explore the effectiveness of our methodology by demonstrating the trade-off between the channel transmission rate and the robustness of the communication. We evaluate MC3 on NVIDIA Orin AGX, NX, and Nano platforms and achieve transmission rates up to 6.4 Kbps with less than 1% error rate. 

Shared memory system-on-chips (SM-SoCs) are ubiquitously employed by a wide range of computing platforms, including edge/IoT devices, autonomous systems, and smartphones. In SM-SoCs, system-wide shared memory enables a convenient and cost-effective mechanism for making data accessible across dozens of processing units (PUs), such as CPU cores and domain-specific accelerators. Due to the diverse computational characteristics of the PUs they embed, SM-SoCs often do not employ a shared last-level cache (LLC). Although covert channel attacks have been widely studied in shared memory systems, high-throughput communication has previously been feasible only by relying on an LLC or by possessing privileged or physical access to the shared memory subsystem. In this study, we introduce a new memory-contention-based covert communication attack, MC3, which specifically targets shared system memory in mobile SoCs. Unlike existing attacks, our approach achieves high-throughput communication without the need for an LLC or elevated access to the system. We explore the effectiveness of our methodology by demonstrating the trade-off between the channel transmission rate and the robustness of the communication. We evaluate MC3 on NVIDIA Orin AGX, NX, and Nano platforms and achieve transmission rates up to 6.4 Kbps with less than 1% error rate. 

Abstract Josephson-CMOS hybrid memory leverages the high speed and low power operation of single-flux quantum logic and the high integration densities of CMOS technology. One of the commonly used type of interface circuits in Josephson-CMOS memory is a Suzuki stack, which is a latching high-voltage driver circuit. Suzuki stack circuits are typically powered by an AC bias voltage that has several limitations such as synchronization and coupling effects. To address these issues, a novel DC-biased Suzuki stack circuit is proposed in this paper. As compared to a conventional AC-biased Suzuki stack circuit, the proposed DC-biased design can provide similar output voltage levels and parameter margins, approximately two times higher operating frequency, and three orders of magnitude lower heat load of bias cables.