CentOS 7 : kernel (CESA-2018:0007) (Meltdown) (Spectre)

Medium Nessus Plugin ID 105588

Synopsis

The remote CentOS host is missing one or more security updates.

Description

An update for kernel is now available for Red Hat Enterprise Linux 7.

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.

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.

Solution

Update the affected kernel packages.

See Also

http://www.nessus.org/u?5cb43fdc

Plugin Details

Severity: Medium

ID: 105588

File Name: centos_RHSA-2018-0007.nasl

Version: 3.9

Type: local

Agent: unix

Published: 2018/01/05

Modified: 2018/05/25

Dependencies: 12634

Risk Information

Risk Factor: Medium

CVSSv2

Base Score: 4.7

Temporal Score: 4.5

Vector: CVSS2#AV:L/AC:M/Au:N/C:C/I:N/A:N

Temporal Vector: CVSS2#E:F/RL:ND/RC:ND

CVSSv3

Base Score: 5.6

Temporal Score: 5.4

Vector: CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

Temporal Vector: CVSS:3.0/E:F/RL:X/RC:X

Vulnerability Information

CPE: p-cpe:/a:centos:centos:kernel, p-cpe:/a:centos:centos:kernel-abi-whitelists, p-cpe:/a:centos:centos:kernel-debug, p-cpe:/a:centos:centos:kernel-debug-devel, p-cpe:/a:centos:centos:kernel-devel, p-cpe:/a:centos:centos:kernel-doc, p-cpe:/a:centos:centos:kernel-headers, p-cpe:/a:centos:centos:kernel-tools, p-cpe:/a:centos:centos:kernel-tools-libs, p-cpe:/a:centos:centos:kernel-tools-libs-devel, p-cpe:/a:centos:centos:perf, p-cpe:/a:centos:centos:python-perf, cpe:/o:centos:centos:7

Required KB Items: Host/local_checks_enabled, Host/CentOS/release, Host/CentOS/rpm-list

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 2018/01/04

Exploitable With

CANVAS (CANVAS)

Reference Information

CVE: CVE-2017-5715, CVE-2017-5753, CVE-2017-5754

RHSA: 2018:0007

IAVA: 2018-A-0019, 2018-A-0020