| Description: | Summary:
The remote host is missing an update for the 'kernel'
package(s) announced via the referenced advisory.
Vulnerability Insight:
The kernel packages contain the Linux
kernel, the core of any Linux operating system. 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. Note: This issue is present in
hardware and cannot be fully fixed via software update. The updated kernel
packages provide software mitigation for this hardware issue at a cost of
potential performance penalty. Please refer to References section for further
information about this issue and the performance impact. In this update
mitigations for x86-64 architecture are provided. Variant CVE-2017-5753 triggers
the speculative execution by performing a bounds-check bypass. 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 boundary and read privileged memory by conducting
targeted cache side-channel attacks. (CVE-2017-5753, Important) 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, Important) Variant CVE-2017-5754 relies on the fact that, on
impacted microprocessors, during speculative execution of instruction permission
faults, exception generation triggered by a faulting access is suppressed until
the retirement of the whole instruction block. In a combination with the fact
that memory accesses may populate the cache even when the block is being dropped
and never committed (executed), an unprivileged local attacker could use this
flaw to read privileged (kernel space) memory by conducting targeted cache
side-channel attacks. (CVE-2017-5754, Important) Note: CVE-2017-5754 affects
Intel x86-64 microprocessors. AMD x86-64 microprocessors are not affected by
this issue. Red Hat would like to thank Google Project Zero for reporting these
issues.
Affected Software/OS:
kernel on Red Hat Enterprise Linux Server (v. 7)
Solution:
Please Install the Updated Packages.
CVSS Score:
4.7
CVSS Vector:
AV:L/AC:M/Au:N/C:C/I:N/A:N
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