CATalyst: Defeating last-level cache side channel attacks in cloud computing
CATalyst: Defeating last-level cache side channel attacks in cloud computing
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DOI：
10.1109/hpca.2016.7446082
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发表时间：
2016-03
期刊：
影响因子：
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通讯作者：
Fangfei Liu;Qian Ge;Y. Yarom;Francis X. McKeen;Carlos V. Rozas;Gernot Heiser;R. Lee
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文献类型：
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作者：
Fangfei Liu;Qian Ge;Y. Yarom;Francis X. McKeen;Carlos V. Rozas;Gernot Heiser;R. Lee
缓存端通道攻击是对多租户公有云平台的严重威胁。过去的工作表明，一个虚拟机(VM)中的秘密信息如何可以由另一个共存的VM使用此类攻击来提取。最近的研究证明了对末级缓存(LLC)进行高带宽、低噪声侧通道攻击的可行性，该缓存由处理器包中的所有内核共享，即使在不同内核上调度虚拟机时也能实现攻击。这篇文章展示了如何使用最近在商用处理器中引入的性能优化特性来抵御这种LLC侧通道攻击。由于大多数云服务器使用英特尔处理器，因此我们将展示如何使用英特尔缓存分配技术(CAT)来提供系统级保护机制，以抵御对共享LLC的侧通道攻击。CAT是一种基于路径的硬件缓存分区机制，用于针对LLC占用实施服务质量。然而，由于它提供的分区数量非常有限，它不能直接用于阻止缓存端通道攻击。我们提出了CATALYST，一种伪锁机制，它使用CAT将LLC划分为硬件-软件混合管理的高速缓存。我们使用Xen和Linux实现了一个概念验证系统，运行在采用Intel处理器的服务器上，并证明了LLC侧通道攻击是可以被击败的。此外，CATALYST在用于安全性时只会造成很小的性能开销，对传统应用程序的影响可以忽略不计。
Cache side channel attacks are serious threats to multi-tenant public cloud platforms. Past work showed how secret information in one virtual machine (VM) can be extracted by another co-resident VM using such attacks. Recent research demonstrated the feasibility of high-bandwidth, low-noise side channel attacks on the last-level cache (LLC), which is shared by all the cores in the processor package, enabling attacks even when VMs are scheduled on different cores. This paper shows how such LLC side channel attacks can be defeated using a performance optimization feature recently introduced in commodity processors. Since most cloud servers use Intel processors, we show how the Intel Cache Allocation Technology (CAT) can be used to provide a system-level protection mechanism to defend from side channel attacks on the shared LLC. CAT is a way-based hardware cache-partitioning mechanism for enforcing quality-of-service with respect to LLC occupancy. However, it cannot be directly used to defeat cache side channel attacks due to the very limited number of partitions it provides. We present CATalyst, a pseudo-locking mechanism which uses CAT to partition the LLC into a hybrid hardware-software managed cache. We implement a proof-of-concept system using Xen and Linux running on a server with Intel processors, and show that LLC side channel attacks can be defeated. Furthermore, CATalyst only causes very small performance overhead when used for security, and has negligible impact on legacy applications.