一句话：提出 Klotski，基于增强 ORAM 与可配置软件缓存，高效混淆执行以抵御 SGX 控制通道攻击。
Intel SGX 为敏感计算提供硬件可信执行环境，但敌手仍可通过受控信道等侧信道攻击破坏 enclave 执行的机密性。现有防御要么保护不完整，要么性能开销过高。本文提出 Klotski，一种高效的混淆执行技术，在安全与性能之间提供可调权衡。Klotski 在高层上模拟安全内存子系统，利用增强的 ORAM 协议将代码和数据载入两个大小可配置的软件缓存，并按可配置间隔重新随机化。为降低软件地址翻译与软件缓存替换带来的开销，Klotski 还引入了多项优化。评估结果表明，Klotski 能抵御受控信道攻击，且性能开销远低于先前方案。
Intel Software Guard eXtensions (SGX) provides a hardware-based trusted execution environment for security-sensitive computations. A program running inside the trusted domain (an enclave) is protected against direct attacks from other software, including privileged software like the operating system (OS), the hypervisor, and low-level firmwares. However, recent research has shown that the SGX is vulnerable to a set of side-channel attacks that allow attackers to compromise the confidentiality of an enclave's execution, such as the controlled-channel attack. Unfortunately, existing defenses either provide an incomplete protection or impose too much performance overhead. In this work, we propose Klotski, an efficient obfuscated execution technique to defeat the controlled-channel attacks with a tunable trade-off between security and performance. From a high level, Klotski emulates a secure memory subsystem. It leverages an enhanced ORAM protocol to load code and data into two software caches with configurable size, which are re-randomized for after a configurable interval. More importantly, Klotski employs several optimizations to reduce the performance overhead caused by software-based address translation and software cache replacement. Evaluation results show that Klotski is secure against controlled-channel attacks and its performance overhead much lower than previous solutions.
@inproceedings{paperbot5403,
title = {Klotski: Efficient Obfuscated Execution against Controlled-Channel Attacks},
author = {Pan Zhang and Chengyu Song and Heng Yin and Deqing Zou and Elaine Shi and Hai Jin},
booktitle = {ASPLOS},
year = {2020},
doi = {10.1145/3373376.3378487}
}