Randomized last-level caches are still vulnerable to cache side-channel attacks! But we can fix it

Wei Song, Boya Li, Zihan Xue, Zhenzhen Li, Wenhao Wang, Peng Liu

Research output: Chapter in Book/Report/Conference proceedingConference contribution

25 Scopus citations


Cache randomization has recently been revived as a promising defense against conflict-based cache side-channel attacks. As two of the latest implementations, CEASER-S and ScatterCache both claim to thwart conflict-based cache side-channel attacks using randomized skewed caches. Unfortunately, our experiments show that an attacker can easily find a usable eviction set within the chosen remap period of CEASER-S and increasing the number of partitions without dynamic remapping, such as ScatterCache, cannot eliminate the threat. By quantitatively analyzing the access patterns left by various attacks in the LLC, we have newly discovered several problems with the hypotheses and implementations of randomized caches, which are also overlooked by the research on conflict-based cache side-channel attacks.However, cache randomization is not a false hope and it is an effective defense that should be widely adopted in future processors. The newly discovered problems are corresponding to flaws associated with the existing implementation of cache randomization and are fixable. Several new defense ideas are proposed in this paper. Our experiments show that all the newly discovered problems are fixed within the current performance budget. We also argue that randomized set-associative caches can be sufficiently strengthened and possess a better chance to be actually adopted in commercial processors than their skewed counterparts because they introduce less overhaul to the existing cache structure.

Original languageEnglish (US)
Title of host publicationProceedings - 2021 IEEE Symposium on Security and Privacy, SP 2021
PublisherInstitute of Electrical and Electronics Engineers Inc.
Number of pages15
ISBN (Electronic)9781728189345
StatePublished - May 2021
Event42nd IEEE Symposium on Security and Privacy, SP 2021 - Virtual, San Francisco, United States
Duration: May 24 2021May 27 2021

Publication series

NameProceedings - IEEE Symposium on Security and Privacy
ISSN (Print)1081-6011


Conference42nd IEEE Symposium on Security and Privacy, SP 2021
Country/TerritoryUnited States
CityVirtual, San Francisco

All Science Journal Classification (ASJC) codes

  • Safety, Risk, Reliability and Quality
  • Software
  • Computer Networks and Communications


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