Ubuntu 20.04 LTS : Linux kernel (OEM) vulnerabilities (USN-4983-1)

high Nessus Plugin ID 150234

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-4983-1 advisory.

- A flaw was found in the Linux kernel in versions before 5.12. The value of internal.ndata, in the KVM API, is mapped to an array index, which can be updated by a user process at anytime which could lead to an out- of-bounds write. The highest threat from this vulnerability is to data integrity and system availability.
(CVE-2021-3501)

- An issue was discovered in the Linux kernel through 5.11.x. kernel/bpf/verifier.c performs undesirable out-of-bounds speculation on pointer arithmetic, leading to side-channel attacks that defeat Spectre mitigations and obtain sensitive information from kernel memory. Specifically, for sequences of pointer arithmetic operations, the pointer modification performed by the first operation is not correctly accounted for when restricting subsequent operations. (CVE-2021-29155)

- kernel/bpf/verifier.c in the Linux kernel through 5.12.1 performs undesirable speculative loads, leading to disclosure of stack content via side-channel attacks, aka CID-801c6058d14a. The specific concern is not protecting the BPF stack area against speculative loads. Also, the BPF stack can contain uninitialized data that might represent sensitive information previously operated on by the kernel. (CVE-2021-31829)

- kernel/bpf/verifier.c in the Linux kernel through 5.12.7 enforces incorrect limits for pointer arithmetic operations, aka CID-bb01a1bba579. This can be abused to perform out-of-bounds reads and writes in kernel memory, leading to local privilege escalation to root. In particular, there is a corner case where the off reg causes a masking direction change, which then results in an incorrect final aux->alu_limit.
(CVE-2021-33200)

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-4983-1

Plugin Details

Severity: High

ID: 150234

File Name: ubuntu_USN-4983-1.nasl

Version: 1.2

Type: local

Agent: unix

Published: 6/4/2021

Updated: 6/4/2021

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

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

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-2021-33200

CVSS v3

Risk Factor: High

Base Score: 7.8

Temporal Score: 6.8

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/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-image-5.10.0-1029-oem, 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

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

Exploit Ease: No known exploits are available

Patch Publication Date: 6/3/2021

Vulnerability Publication Date: 4/20/2021

Reference Information

CVE: CVE-2021-3501, CVE-2021-29155, CVE-2021-31829, CVE-2021-33200

USN: 4983-1