Amazon Linux AMI : kernel (ALAS-2018-956) (Dirty COW) (Spectre)

high Nessus Plugin ID 106933
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The calculated severity for Plugins has been updated to use CVSS v3 by default. Plugins that do not have a CVSS v3 score will fall back to CVSS v2 for calculating severity. Severity display preferences can be toggled in the settings dropdown.


The remote Amazon Linux AMI host is missing a security update.


Kernel address information leak in drivers/acpi/sbshc.c:acpi_smbus_hc_add() function potentially allowing KASLR bypass

The acpi_smbus_hc_add function in drivers/acpi/sbshc.c in the Linux kernel, through 4.14.15, allows local users to obtain sensitive address information by reading dmesg data from an SBS HC printk call.(CVE-2018-5750)

Improper sorting of GIDs in nfsd can lead to incorrect permissions being applied

Linux kernel contains a Incorrect Access Control vulnerability in NFS server (nfsd) that can result in remote users reading or writing files they should not be able to via NFS. This attack appear to be exploitable via NFS server must export a filesystem with the 'rootsquash' options enabled. This vulnerability appears to have been fixed in after commit 1995266727fa.(CVE-2018-1000028)

Stack-based out-of-bounds read via vmcall instruction

Linux kernel compiled with the KVM virtualization (CONFIG_KVM) support is vulnerable to an out-of-bounds read access issue. It could occur when emulating vmcall instructions invoked by a guest. A guest user/process could use this flaw to disclose kernel memory bytes.(CVE-2017-17741)

The pmd can become dirty without going through a COW cycle

A flaw was found in the patches used to fix the 'dirtycow' vulnerability (CVE-2016-5195). An attacker, able to run local code, can exploit a race condition in transparent huge pages to modify usually read-only huge pages.(CVE-2017-1000405)

Speculative execution bounds-check bypass

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-2017-5753 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)

drivers/block/loop.c mishandles lo_release serialization allowing denial-of-service

A flaw was found in the Linux kernel's handling of loopback devices.
An attacker, who has permissions to setup loopback disks, may create a denial of service or other unspecified actions. (CVE-2018-5344)


Run 'yum update kernel' to update your system.

See Also

Plugin Details

Severity: High

ID: 106933

File Name: ala_ALAS-2018-956.nasl

Version: 3.7

Type: local

Agent: unix

Published: 2/22/2018

Updated: 4/5/2019

Dependencies: ssh_get_info.nasl

Risk Information


Risk Factor: High

Score: 8.9


Risk Factor: Medium

Base Score: 6.9

Temporal Score: 6

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

Temporal Vector: E:H/RL:OF/RC:C


Risk Factor: High

Base Score: 7.8

Temporal Score: 7.5

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

Temporal Vector: E:H/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:kernel, p-cpe:/a:amazon:linux:kernel-debuginfo, p-cpe:/a:amazon:linux:kernel-debuginfo-common-i686, p-cpe:/a:amazon:linux:kernel-debuginfo-common-x86_64, p-cpe:/a:amazon:linux:kernel-devel, p-cpe:/a:amazon:linux:kernel-doc, p-cpe:/a:amazon:linux:kernel-headers, p-cpe:/a:amazon:linux:kernel-tools, p-cpe:/a:amazon:linux:kernel-tools-debuginfo, p-cpe:/a:amazon:linux:kernel-tools-devel, p-cpe:/a:amazon:linux:perf, p-cpe:/a:amazon:linux:perf-debuginfo, cpe:/o:amazon:linux

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

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 2/20/2018

Exploitable With


Reference Information

CVE: CVE-2017-1000405, CVE-2017-17741, CVE-2017-5753, CVE-2018-1000028, CVE-2018-5344, CVE-2018-5750

ALAS: 2018-956

IAVA: 2018-A-0020