Ubuntu 20.04 LTS : Linux kernel vulnerabilities (USN-5072-1)

high Nessus Plugin ID 153179

Synopsis

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

Description

The remote Ubuntu 20.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-5072-1 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 virt_ext field, this issue could allow a malicious L1 to disable both VMLOAD/VMSAVE intercepts and VLS (Virtual VMLOAD/VMSAVE) 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. (CVE-2021-3656)

- 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)

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

Solution

Update the affected packages.

See Also

https://ubuntu.com/security/notices/USN-5072-1

Plugin Details

Severity: High

ID: 153179

File Name: ubuntu_USN-5072-1.nasl

Version: 1.5

Type: local

Agent: unix

Published: 9/9/2021

Updated: 3/14/2022

Supported Sensors: Frictionless Assessment Agent, Frictionless Assessment AWS, Frictionless Assessment Azure, Nessus Agent

Risk Information

VPR

Risk Factor: High

Score: 8.1

CVSS v2

Risk Factor: High

Base Score: 7.2

Temporal Score: 5.3

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

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

CVSS Score Source: CVE-2021-3656

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: E:U/RL:O/RC:C

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:20.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:linux-azure, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.8-cloud-tools-5.8.0-1041, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.8-headers-5.8.0-1041, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.8-tools-5.8.0-1041, p-cpe:/a:canonical:ubuntu_linux:linux-buildinfo-5.10.0-1045-oem, p-cpe:/a:canonical:ubuntu_linux:linux-buildinfo-5.8.0-1041-azure, p-cpe:/a:canonical:ubuntu_linux:linux-cloud-tools-5.8.0-1041-azure, p-cpe:/a:canonical:ubuntu_linux:linux-cloud-tools-azure, p-cpe:/a:canonical:ubuntu_linux:linux-headers-5.10.0-1045-oem, p-cpe:/a:canonical:ubuntu_linux:linux-headers-5.8.0-1041-azure, p-cpe:/a:canonical:ubuntu_linux:linux-headers-azure, p-cpe:/a:canonical:ubuntu_linux:linux-headers-oem-20.04, p-cpe:/a:canonical:ubuntu_linux:linux-headers-oem-20.04-edge, p-cpe:/a:canonical:ubuntu_linux:linux-headers-oem-20.04b, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.10.0-1045-oem, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.8.0-1041-azure, p-cpe:/a:canonical:ubuntu_linux:linux-image-azure, p-cpe:/a:canonical:ubuntu_linux:linux-image-oem-20.04, p-cpe:/a:canonical:ubuntu_linux:linux-image-oem-20.04-edge, p-cpe:/a:canonical:ubuntu_linux:linux-image-oem-20.04b, p-cpe:/a:canonical:ubuntu_linux:linux-image-unsigned-5.10.0-1045-oem, p-cpe:/a:canonical:ubuntu_linux:linux-image-unsigned-5.8.0-1041-azure, p-cpe:/a:canonical:ubuntu_linux:linux-modules-5.10.0-1045-oem, p-cpe:/a:canonical:ubuntu_linux:linux-modules-5.8.0-1041-azure, p-cpe:/a:canonical:ubuntu_linux:linux-modules-extra-5.8.0-1041-azure, p-cpe:/a:canonical:ubuntu_linux:linux-modules-extra-azure, p-cpe:/a:canonical:ubuntu_linux:linux-oem-20.04, p-cpe:/a:canonical:ubuntu_linux:linux-oem-20.04-edge, p-cpe:/a:canonical:ubuntu_linux:linux-oem-20.04b, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.10-headers-5.10.0-1045, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.10-tools-5.10.0-1045, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.10-tools-host, p-cpe:/a:canonical:ubuntu_linux:linux-tools-5.10.0-1045-oem, p-cpe:/a:canonical:ubuntu_linux:linux-tools-5.8.0-1041-azure, p-cpe:/a:canonical:ubuntu_linux:linux-tools-azure, p-cpe:/a:canonical:ubuntu_linux:linux-tools-oem-20.04, p-cpe:/a:canonical:ubuntu_linux:linux-tools-oem-20.04-edge, p-cpe:/a:canonical:ubuntu_linux:linux-tools-oem-20.04b

Required KB Items: Host/cpu, Host/Ubuntu, Host/Ubuntu/release, Host/Debian/dpkg-l

Exploit Ease: No known exploits are available

Patch Publication Date: 9/8/2021

Vulnerability Publication Date: 9/8/2021

Reference Information

CVE: CVE-2021-3653, CVE-2021-3656

USN: 5072-1