Securing Embedded System from Code Reuse Attacks: A Lightweight Scheme with Hardware Assistance

The growing prevalence of embedded systems in various applications has raised concerns about their vulnerability to malicious code reuse attacks. Current software-based and hardware-assisted security techniques struggle to detect or block these attacks with minor performance and implementation overhead. To address this issue, this paper presents a lightweight hardware-assisted scheme to enhance the security of embedded systems against code reuse attacks. We develop an on-chip lightweight hardware shadow stack to validate target addresses at runtime for backward-edge control flow integrity, which backs up valid return addresses during function calls and automatically verifies actual return addresses during the return phase. Additionally, we propose a lightweight stream cipher circuit that encrypts and decrypts critical stack data related to control flow manipulation, preventing attackers from analyzing or tampering with them. When designing and implementing the security mechanism for embedded systems, we fully consider the constraints of limited system resources and performance, optimizing both the architecture design and implementation of the proposed hardware. Finally, we integrate both the proposed lightweight hardware shadow stack and the runtime data encryption hardware into the OR1200 processor. We have verified the system security function on the Terasic DE1-SoC FPGA platform and evaluated the system performance as well as implementation overhead. The results show that the proposed lightweight hardware-assisted scheme can provide a dedicated defense capability against code reuse attacks for embedded systems, with an average system performance overhead of 0.39% and an area footprint of 0.316 mm(2).