Amazon Linux 2 : kernel (ALAS-2021-1704)

high Nessus Plugin ID 153418
New! Plugin Severity Now Using CVSS v3

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.

Synopsis

The remote Amazon Linux 2 host is missing a security update.

Description

The version of kernel installed on the remote host is prior to 4.14.246-187.474. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2-2021-1704 advisory.

- A flaw was found in the KVM's AMD code for supporting SVM nested virtualization. The flaw occurs when processing the VMCB (virtual machine control block) provided by the L1 guest to spawn/handle a nested guest (L2). Due to improper validation of the int_ctl field, this issue could allow a malicious L1 to enable AVIC support (Advanced Virtual Interrupt Controller) for the L2 guest. As a result, the L2 guest would be allowed to read/write physical pages of the host, resulting in a crash of the entire system, leak of sensitive data or potential guest-to-host escape. This flaw affects Linux kernel versions prior to 5.14-rc7. (CVE-2021-3653)

- arch/x86/kvm/mmu/paging_tmpl.h in the Linux kernel before 5.12.11 incorrectly computes the access permissions of a shadow page, leading to a missing guest protection page fault. (CVE-2021-38198)

- A race condition was discovered in ext4_write_inline_data_end in fs/ext4/inline.c in the ext4 subsystem in the Linux kernel through 5.13.13. (CVE-2021-40490)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Run 'yum update kernel' to update your system.

See Also

https://access.redhat.com/security/cve/CVE-2021-40490

https://access.redhat.com/security/cve/CVE-2021-3653

https://access.redhat.com/security/cve/CVE-2021-3656

https://access.redhat.com/security/cve/CVE-2021-3732

https://access.redhat.com/security/cve/CVE-2021-3753

https://access.redhat.com/security/cve/CVE-2021-38198

https://alas.aws.amazon.com/AL2/ALAS-2021-1704.html

Plugin Details

Severity: High

ID: 153418

File Name: al2_ALAS-2021-1704.nasl

Version: 1.6

Type: local

Agent: unix

Published: 9/16/2021

Updated: 10/12/2021

Dependencies: ssh_get_info.nasl

Risk Information

CVSS Score Source: CVE-2021-3653

VPR

Risk Factor: High

Score: 7.3

CVSS v2

Risk Factor: Medium

Base Score: 6.1

Temporal Score: 4.5

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

Temporal Vector: CVSS2#E:U/RL:OF/RC:C

CVSS v3

Risk Factor: High

Base Score: 8.8

Temporal Score: 7.7

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

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:2.3:o:amazon:linux:2:*:*:*:*:*:*:*, p-cpe:2.3:a:amazon:linux:kernel:*:*:*:*:*:*:*, p-cpe:2.3:a:amazon:linux:kernel-debuginfo:*:*:*:*:*:*:*, p-cpe:2.3:a:amazon:linux:kernel-debuginfo-common-x86_64:*:*:*:*:*:*:*, p-cpe:2.3:a:amazon:linux:kernel-devel:*:*:*:*:*:*:*, p-cpe:2.3:a:amazon:linux:kernel-headers:*:*:*:*:*:*:*, p-cpe:2.3:a:amazon:linux:kernel-tools:*:*:*:*:*:*:*, p-cpe:2.3:a:amazon:linux:kernel-tools-debuginfo:*:*:*:*:*:*:*, p-cpe:2.3:a:amazon:linux:kernel-tools-devel:*:*:*:*:*:*:*, p-cpe:2.3:a:amazon:linux:perf:*:*:*:*:*:*:*, p-cpe:2.3:a:amazon:linux:perf-debuginfo:*:*:*:*:*:*:*, p-cpe:2.3:a:amazon:linux:python-perf:*:*:*:*:*:*:*, p-cpe:2.3:a:amazon:linux:python-perf-debuginfo:*:*:*:*:*:*:*, p-cpe:2.3:a:amazon:linux:kernel-debuginfo-common-aarch64:*:*:*:*:*:*:*, p-cpe:2.3:a:amazon:linux:kernel-livepatch-4.14.246-187.474:*:*:*:*:*:*:*

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

Exploit Ease: No known exploits are available

Patch Publication Date: 9/8/2021

Vulnerability Publication Date: 8/8/2021

Reference Information

CVE: CVE-2021-38198, CVE-2021-3656, CVE-2021-3653, CVE-2021-40490, CVE-2021-3732, CVE-2021-3753

ALAS: 2021-1704