Red Hat Security Advisory 2018-0040-01 - The microcode_ctl packages provide microcode updates for Intel and AMD processors. Security Fix: An industry-wide issue was found in the way many modern microprocessor designs have implemented speculative execution of instructions. There are three primary variants of the issue which differ in the way the speculative execution can be exploited. Variant CVE-2017-5715 triggers the speculative execution by utilizing branch target injection. It relies on the presence of a precisely-defined instruction sequence in the privileged code as well as the fact that memory accesses may cause allocation into the microprocessor's data cache even for speculatively executed instructions that never actually commit. As a result, an unprivileged attacker could use this flaw to cross the syscall and guest/host boundaries and read privileged memory by conducting targeted cache side-channel attacks.
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Red Hat Security Advisory
Synopsis: Important: microcode_ctl security update
Advisory ID: RHSA-2018:0040-01
Product: Red Hat Enterprise Linux
Advisory URL: https://access.redhat.com/errata/RHSA-2018:0040
Issue date: 2018-01-04
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1. Summary:
An update for microcode_ctl is now available for Red Hat Enterprise Linux
6.5 Advanced Update Support.
Red Hat Product Security has rated this update as having a security impact
of Important. A Common Vulnerability Scoring System (CVSS) base score,
which gives a detailed severity rating, is available for each vulnerability
from the CVE link(s) in the References section.
2. Relevant releases/architectures:
Red Hat Enterprise Linux Server AUS (v. 6.5) - x86_64
3. Description:
The microcode_ctl packages provide microcode updates for Intel and AMD
processors.
Security Fix(es):
* An industry-wide issue was found in the way many modern microprocessor
designs have implemented speculative execution of instructions (a commonly
used performance optimization). There are three primary variants of the
issue which differ in the way the speculative execution can be exploited.
Variant CVE-2017-5715 triggers the speculative execution by utilizing
branch target injection. It relies on the presence of a precisely-defined
instruction sequence in the privileged code as well as the fact that memory
accesses may cause allocation into the microprocessor's data cache even for
speculatively executed instructions that never actually commit (retire). As
a result, an unprivileged attacker could use this flaw to cross the syscall
and guest/host boundaries and read privileged memory by conducting targeted
cache side-channel attacks. (CVE-2017-5715)
Note: This is the microcode counterpart of the CVE-2017-5715 kernel
mitigation.
Red Hat would like to thank Google Project Zero for reporting this issue.
4. Solution:
For details on how to apply this update, which includes the changes
described in this advisory, refer to:
https://access.redhat.com/articles/11258
Note: a system reboot is necessary for this update to take effect.
5. Bugs fixed (https://bugzilla.redhat.com/):
1519780 - CVE-2017-5715 hw: cpu: speculative execution branch target injection
6. Package List:
Red Hat Enterprise Linux Server AUS (v. 6.5):
Source:
microcode_ctl-1.17-17.el6_5.2.src.rpm
x86_64:
microcode_ctl-1.17-17.el6_5.2.x86_64.rpm
microcode_ctl-debuginfo-1.17-17.el6_5.2.x86_64.rpm
These packages are GPG signed by Red Hat for security. Our key and
details on how to verify the signature are available from
https://access.redhat.com/security/team/key/
7. References:
https://access.redhat.com/security/updates/classification/#important
https://access.redhat.com/security/vulnerabilities/speculativeexecution
https://access.redhat.com/security/cve/CVE-2017-5715
8. Contact:
The Red Hat security contact is <secalert@redhat.com>. More contact
details at https://access.redhat.com/security/team/contact/
Copyright 2018 Red Hat, Inc.
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