Speculative interference attacks: Breaking invisible speculation schemes

Mohammad Behnia, Prateek Sahu, Riccardo Paccagnella, Jiyong Yu, Zirui Neil Zhao, Xiang Zou, Thomas Unterluggauer, Josep Torrellas, Carlos Rozas, Adam Morrison, Frank McKeen, Fangfei Liu, Ron Gabor, Christopher W. Fletcher, Abhishek Basak, Alaa Alameldeen

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

39 Scopus citations

Abstract

Recent security vulnerabilities that target speculative execution (e.g., Spectre) present a significant challenge for processor design. These highly publicized vulnerabilities use speculative execution to learn victim secrets by changing the cache state. As a result, recent computer architecture research has focused on invisible speculation mechanisms that attempt to block changes in cache state due to speculative execution. Prior work has shown significant success in preventing Spectre and other attacks at modest performance costs. In this paper, we introduce speculative interference attacks, which show that prior invisible speculation mechanisms do not fully block speculation-based attacks that use cache state. We make two key observations. First, mis-speculated younger instructions can change the timing of older, bound-to-retire instructions, including memory operations. Second, changing the timing of a memory operation can change the order of that memory operation relative to other memory operations, resulting in persistent changes to the cache state. Using both of these observations, we demonstrate (among other attack variants) that secret information accessed by mis-speculated instructions can change the order of bound-to-retire loads. Load timing changes can therefore leave secret-dependent changes in the cache, even in the presence of invisible speculation mechanisms. We show that this problem is not easy to fix. Speculative interference converts timing changes to persistent cache-state changes, and timing is typically ignored by many cache-based defenses. We develop a framework to understand the attack and demonstrate concrete proof-of-concept attacks against invisible speculation mechanisms. We conclude with a discussion of security definitions that are sufficient to block the attacks, along with preliminary defense ideas based on those definitions.

Original languageEnglish
Title of host publicationProceedings of the 26th ACM International Conference on Architectural Support for Programming Languages and Operating Systems, ASPLOS 2021
PublisherAssociation for Computing Machinery
Pages1046-1060
Number of pages15
ISBN (Electronic)9781450383172
DOIs
StatePublished - 19 Apr 2021
Event26th ACM International Conference on Architectural Support for Programming Languages and Operating Systems, ASPLOS 2021 - Virtual, Online, United States
Duration: 19 Apr 202123 Apr 2021

Publication series

NameInternational Conference on Architectural Support for Programming Languages and Operating Systems - ASPLOS

Conference

Conference26th ACM International Conference on Architectural Support for Programming Languages and Operating Systems, ASPLOS 2021
Country/TerritoryUnited States
CityVirtual, Online
Period19/04/2123/04/21

Funding

FundersFunder number
Intel Strategic Research Alliance
National Science Foundation1954521, 1942888
Israel Science Foundation2005/17

    Keywords

    • invisible speculation
    • microarchitectural covert channels
    • speculative execution attacks

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