Holistic Control-Flow Protection on Real-Time Embedded Systems with Kage


Yufei Du, University of North Carolina at Chapel Hill; Zhuojia Shen, Komail Dharsee, and Jie Zhou, University of Rochester; Robert J. Walls, Worcester Polytechnic Institute; John Criswell, University of Rochester


This paper presents Kage: a system that protects the control data of both application and kernel code on microcontroller-based embedded systems. Kage consists of a Kage-compliant embedded OS that stores all control data in separate memory regions from untrusted data, a compiler that transforms code to protect these memory regions efficiently and to add forward-edge control-flow integrity checks, and a secure API that allows safe updates to the protected data. We implemented Kage as an extension to FreeRTOS, an embedded real-time operating system. We evaluated Kage's performance using the CoreMark benchmark. Kage incurred a 5.2% average runtime overhead and 49.8% code size overhead. Furthermore, the code size overhead was only 14.2% when compared to baseline FreeRTOS with the MPU enabled. We also evaluated Kage's security guarantees by measuring and analyzing reachable code-reuse gadgets. Compared to FreeRTOS, Kage reduces the number of reachable gadgets from 2,276 to 27, and the remaining 27 gadgets cannot be stitched together to launch a practical attack.

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@inproceedings {277140,
title = {Holistic {Control-Flow} Protection on {Real-Time} Embedded Systems with Kage},
booktitle = {31st USENIX Security Symposium (USENIX Security 22)},
year = {2022},
address = {Boston, MA},
url = {https://www.usenix.org/conference/usenixsecurity22/presentation/du},
publisher = {USENIX Association},
month = aug,