Shielding Software From Privileged Side-Channel Attacks


Xiaowan Dong, Zhuojia Shen, and John Criswell, University of Rochester; Alan L. Cox, Rice University; Sandhya Dwarkadas, University of Rochester


Commodity operating system (OS) kernels, such as Windows, Mac OS X, Linux, and FreeBSD, are susceptible to numerous security vulnerabilities. Their monolithic design gives successful attackers complete access to all application data and system resources. Shielding systems such as InkTag, Haven, and Virtual Ghost protect sensitive application data from compromised OS kernels. However, such systems are still vulnerable to side-channel attacks. Worse yet, compromised OS kernels can leverage their control over privileged hardware state to exacerbate existing side channels; recent work has shown that a compromised OS kernel can steal entire documents via side channels.

This paper presents defenses against page table and last-level cache (LLC) side-channel attacks launched by a compromised OS kernel. Our page table defenses restrict the OS kernel's ability to read and write page table pages and defend against page allocation attacks, and our LLC defenses utilize the Intel Cache Allocation Technology along with memory isolation primitives. We prototype our solution in a system we call Apparition, building on an optimized version of Virtual Ghost. Our evaluation shows that our side-channel defenses add 1% to 18% (with up to 86% for one application) overhead to the optimized Virtual Ghost (relative to the native kernel) on real-world applications.

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@inproceedings {217468,
author = {Xiaowan Dong and Zhuojia Shen and John Criswell and Alan L. Cox and Sandhya Dwarkadas},
title = {Shielding Software From Privileged Side-Channel Attacks},
booktitle = {27th {USENIX} Security Symposium ({USENIX} Security 18)},
year = {2018},
isbn = {978-1-931971-46-1},
address = {Baltimore, MD},
pages = {1441--1458},
url = {},
publisher = {{USENIX} Association},