Flush+Flush: A fast and stealthy cache attack

Daniel Gruss*, Clémentine Maurice, Klaus Wagner, Stefan Mangard

*Corresponding author for this work

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


Research on cache attacks has shown that CPU caches leak significant information. Proposed detection mechanisms assume that all cache attacks cause more cache hits and cache misses than benign applications and use hardware performance counters for detection. In this article, we show that this assumption does not hold by developing a novel attack technique: the Flush+Flush attack. The Flush+Flush attack only relies on the execution time of the flush instruction, which depends on whether data is cached or not. Flush+Flush does not make any memory accesses, contrary to any other cache attack. Thus, it causes no cache misses at all and the number of cache hits is reduced to a minimum due to the constant cache flushes. Therefore, Flush+Flush attacks are stealthy, i.e., the spy process cannot be detected based on cache hits and misses, or state-of-the-art detection mechanisms. The Flush+Flush attack runs in a higher frequency and thus is faster than any existing cache attack. With 496 KB/s in a cross-core covert channel it is 6.7 times faster than any previously published cache covert channel.

Original languageEnglish
Title of host publicationDetection of Intrusions and Malware, and Vulnerability Assessment - 13th International Conference, DIMVA 2016, Proceedings
PublisherSpringer-Verlag Italia
Number of pages21
ISBN (Print)9783319406664
Publication statusPublished - 2016
Event13th International Conference on Detection of Intrusions and Malware, and Vulnerability Assessment, DIMVA 2016 - San Sebastian, Spain
Duration: 7 Jul 20168 Jul 2016

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
ISSN (Print)03029743
ISSN (Electronic)16113349


Conference13th International Conference on Detection of Intrusions and Malware, and Vulnerability Assessment, DIMVA 2016
CitySan Sebastian

ASJC Scopus subject areas

  • Theoretical Computer Science
  • Computer Science(all)


Dive into the research topics of 'Flush+Flush: A fast and stealthy cache attack'. Together they form a unique fingerprint.

Cite this