Bug 1532127

Summary: firefox: mitigations against spectre via javascript
Product: [Other] Security Response Reporter: Sam Fowler <sfowler>
Component: vulnerabilityAssignee: Red Hat Product Security <security-response-team>
Status: CLOSED NOTABUG QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: gotiwari, jgrulich, jhorak, mvyas, sfowler, stransky, tpopela
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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Fixed In Version: firefox 57.0.4 Doc Type: If docs needed, set a value
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Last Closed: 2018-01-08 05:09:18 UTC Type: ---
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On:    
Bug Blocks: 1533340, 1534345    

Description Sam Fowler 2018-01-08 05:05:17 UTC 
Mozilla has issued an advisory (mfsa2018-01) for Firefox 57.0.4 that implements a short term mitigation for spectre based javascript attacks.

CVE-2017-5754 CVE-2017-5753

References:
https://www.mozilla.org/en-US/security/advisories/mfsa2018-01/
Comment 5 Tomas Hoger 2018-01-10 13:19:14 UTC 
(In reply to Sam Fowler from comment #3)
> "The precision of performance.now() has been reduced from 5μs to 20μs"

According to the following Mozilla blog post:

https://blog.mozilla.org/security/2018/01/03/mitigations-landing-new-class-timing-attack/

this mitigation is going to be include in 52 ESR in version 52.6 ESR.
Comment 6 Huzaifa S. Sidhpurwala 2018-01-11 05:33:23 UTC 
Statement:

Mozilla has confirmed that similar to "Meltdown" and "Spectre" which are a new class of timing attacks which affect modern CPUs, it is possible to use similar techniques to read private web content between different origins. 

Since this new class of attacks involves measuring precise time intervals, as a partial, short-term, mitigation Mozilla is disabling or reducing the precision of several time sources in Firefox.

Two such sources were identified:

1. Explicit source like "performance.now()".
2. Implicit source like SharedArrayBuffer.

The versions of Mozilla Firefox shipped with Red Hat Enterprise Linux does not enable SharedArrayBuffer. Also the first risk factor listed above (namely performance.now()) has a much lower security impact and will be addressed in an upcoming security errata by Mozilla.
Comment 7 Huzaifa S. Sidhpurwala 2018-01-11 05:33:59 UTC 
External Reference:

https://www.mozilla.org/en-US/security/advisories/mfsa2018-01/
https://blog.mozilla.org/security/2018/01/03/mitigations-landing-new-class-timing-attack/