Speculative Store Bypass
{{short description|Processor security vulnerability}}
{{See also|Speculative execution CPU vulnerabilities}}
{{Use dmy dates|date=July 2019|cs1-dates=y}}
Speculative Store Bypass (SSB) ({{CVE|2018-3639}}) is the name given to a hardware security vulnerability and its exploitation that takes advantage of speculative execution in a similar way to the Meltdown and Spectre security vulnerabilities. It affects the ARM, AMD and Intel families of processors. It was discovered by researchers at Microsoft Security Response Center and Google Project Zero (GPZ). After being leaked on 3 May 2018 as part of a group of eight additional Spectre-class flaws provisionally named Spectre-NG, it was first disclosed to the public as "Variant 4" on 21 May 2018, alongside a related speculative execution vulnerability designated "Variant 3a".
Details
Speculative execution exploit Variant 4, is referred to as Speculative Store Bypass (SSB), and has been assigned {{CVE|2018-3639}}. SSB is named Variant 4, but it is the fifth variant in the Spectre-Meltdown class of vulnerabilities.
- "Slowly" store a value at a memory location
- "Quickly" load that value from that memory location
- Utilize the value that was just read to disrupt the cache in a detectable way
Impact and mitigation
Intel claims that web browsers that are already patched to mitigate Spectre Variants 1 and 2 are partially protected against Variant 4. Intel said in a statement that the likelihood of end users being affected was "low" and that not all protections would be on by default due to some impact on performance. The Chrome JavaScript team confirmed that effective mitigation of Variant 4 in software is infeasible, in part due to performance impact.
Intel is planning to address Variant 4 by releasing a microcode patch that creates a new hardware flag named Speculative Store Bypass Disable (SSBD). A stable microcode patch is yet to be delivered, with Intel suggesting that the patch will be ready "in the coming weeks".{{Update inline|date=November 2018}} Many operating system vendors will be releasing software updates to assist with mitigating Variant 4; however, microcode/firmware updates are required for the software updates to have an effect.
Speculative execution exploit variants
References
{{reflist|refs=
{{cite web |title=Predictable problems - New speculative-execution vulnerability strikes AMD, ARM, and Intel |author-first=Peter |author-last=Bright |date=2018-05-22 |publisher=Ars Technica |url=https://arstechnica.com/gadgets/2018/05/new-speculative-execution-vulnerability-strikes-amd-arm-and-intel/ |access-date=2018-05-25 |url-status=live |archive-url=https://web.archive.org/web/20180526085252/https://arstechnica.com/gadgets/2018/05/new-speculative-execution-vulnerability-strikes-amd-arm-and-intel/ |archive-date=2018-05-26}}
{{cite web |date=2018-05-21 |author=Ubuntu Community |url=https://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/Variant4 |title=Variant4 |access-date=2018-05-21 |url-status=live |archive-url=https://web.archive.org/web/20180522065023/https://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/Variant4 |archive-date=2018-05-22}}
{{cite journal |title=Super-GAU für Intel: Weitere Spectre-Lücken im Anflug |language=German |author-first=Jürgen |author-last=Schmidt |journal=c't - magazin für computertechnik |publisher=Heise Online |date=2018-05-03 |url=https://www.heise.de/ct/artikel/Super-GAU-fuer-Intel-Weitere-Spectre-Luecken-im-Anflug-4039134.html |access-date=2018-05-03 |url-status=live |archive-url=https://web.archive.org/web/20180505150707/https://www.heise.de/ct/artikel/Super-GAU-fuer-Intel-Weitere-Spectre-Luecken-im-Anflug-4039134.html |archive-date=2018-05-05}} {{cite journal |title=Exclusive: Spectre-NG - Multiple new Intel CPU flaws revealed, several serious |author-first=Jürgen |author-last=Schmidt |journal=c't - magazin für computertechnik |publisher=Heise Online |date=2018-05-03 |url=https://www.heise.de/ct/artikel/Exclusive-Spectre-NG-Multiple-new-Intel-CPU-flaws-revealed-several-serious-4040648.html |access-date=2018-05-04 |url-status=live |archive-url=https://web.archive.org/web/20180505113543/https://www.heise.de/ct/artikel/Exclusive-Spectre-NG-Multiple-new-Intel-CPU-flaws-revealed-several-serious-4040648.html |archive-date=2018-05-05}}
{{cite journal |title=Spectre-NG: Intel-Prozessoren von neuen hochriskanten Sicherheitslücken betroffen, erste Reaktionen von AMD und Intel |language=German |author-first=Martin |author-last=Fischer |journal=c't - magazin für computertechnik |publisher=Heise Online |date=2018-05-03 |url=https://www.heise.de/security/meldung/Spectre-NG-Intel-Prozessoren-von-neuen-hochriskanten-Sicherheitsluecken-betroffen-4039302.html |access-date=2018-05-04 |url-status=live |archive-url=https://web.archive.org/web/20180505131934/https://www.heise.de/security/meldung/Spectre-NG-Intel-Prozessoren-von-neuen-hochriskanten-Sicherheitsluecken-betroffen-4039302.html |archive-date=2018-05-05}}
{{cite web |author-last=Tung |author-first=Liam |title=Are 8 new 'Spectre-class' flaws about to be exposed? Intel confirms it's readying fixes |date=2018-05-04 |url=https://www.zdnet.com/article/are-8-new-spectre-class-flaws-about-to-be-exposed/ |website=ZDNet |access-date=2018-03-04 |url-status=live |archive-url=https://web.archive.org/web/20180522152328/https://www.zdnet.com/article/are-8-new-spectre-class-flaws-about-to-be-exposed/ |archive-date=2018-05-22}}
{{cite web |title=Google and Microsoft disclose new CPU flaw, and the fix can slow machines down - New firmware updates are on the way |author-last=Warren |author-first=Tom |date=2018-05-21 |work=The Verge |url=https://www.theverge.com/2018/5/21/17377994/google-microsoft-cpu-vulnerability-speculative-store-bypass-variant-4 |access-date=2018-05-22 |url-status=live |archive-url=https://web.archive.org/web/20180526084527/https://www.theverge.com/2018/5/21/17377994/google-microsoft-cpu-vulnerability-speculative-store-bypass-variant-4 |archive-date=2018-05-26}}
{{cite web |title=New Spectre-like bug could mean more performance-degrading patches |author-last=Martindale |author-first=Jon |date=2018-05-22 |work=Digital Trends |url=https://www.digitaltrends.com/computing/intel-spectre-like-bug-firmware/ |access-date=2018-05-22 |url-status=live |archive-url=https://web.archive.org/web/20180526090443/https://www.digitaltrends.com/computing/intel-spectre-like-bug-firmware/ |archive-date=2018-05-26}}
{{cite web |title=Q2 2018 Speculative Execution Side Channel Update |date=2018-05-21 |publisher=Intel |url=https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00115.html |access-date=2018-05-21 |url-status=live |archive-url=https://web.archive.org/web/20180522064808/https://www.intel.com/content/www/us/en/security-center/advisory/intel-sa-00115.html |archive-date=2018-05-22}}
{{cite magazine |title=After Meltdown and Spectre, Another Scary Chip Flaw Emerges |author-first=Lily Hay |author-last=Newman |date=2018-05-21 |magazine=Wired |url=https://www.wired.com/story/speculative-store-bypass-spectre-meltdown-vulnerability/ |access-date=2018-05-26 |url-status=live |archive-url=https://web.archive.org/web/20180526085509/https://www.wired.com/story/speculative-store-bypass-spectre-meltdown-vulnerability/ |archive-date=2018-05-26}}
{{cite web |publisher=Microsoft Security Response Center |title=Analysis and mitigation of speculative store bypass (CVE-2018-3639) |author-first=Matt |author-last=Miller |at=Speculative store bypass disable (SSBD) section |url=https://blogs.technet.microsoft.com/srd/2018/05/21/analysis-and-mitigation-of-speculative-store-bypass-cve-2018-3639/ |access-date=2018-05-21 |url-status=live |archive-url=https://web.archive.org/web/20180522070214/https://blogs.technet.microsoft.com/srd/2018/05/21/analysis-and-mitigation-of-speculative-store-bypass-cve-2018-3639/ |archive-date=2018-05-22}}
{{cite web |at=Resolve tab |date=2018-05-21 |title=Kernel Side-Channel Attack using Speculative Store Bypass - CVE-2018-3639 |publisher=RedHat |url=https://access.redhat.com/security/vulnerabilities/ssbd |access-date=2018-05-22 |url-status=live |archive-url=https://web.archive.org/web/20180522065511/https://access.redhat.com/security/vulnerabilities/ssbd |archive-date=2018-05-22}}
{{cite web |title=Speculative Execution Side Channel Mitigations |version=Revision 2.0 |date=May 2018 |orig-year=January 2018 |id=Document Number: 336996-002 |publisher=Intel |url=https://software.intel.com/sites/default/files/managed/c5/63/336996-Speculative-Execution-Side-Channel-Mitigations.pdf |access-date=2018-05-26}}
}}
See also
External links
- [https://spectreattack.com/ Website detailing the Meltdown and Spectre vulnerabilities, hosted by Graz University of Technology]
- [https://googleprojectzero.blogspot.co.at/2018/01/reading-privileged-memory-with-side.html Google Project Zero write-up]
- [https://www.grc.com/inspectre.htm Meltdown/Spectre Checker] Gibson Research Corporation
{{Speculative execution exploits}}
{{Hacking in the 2010s}}