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Ubuntu 18.04 LTS / 20.04 LTS : Linux kernel vulnerabilities (USN-4887-1)

high Nessus Plugin ID 148034

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Synopsis

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

Description

The remote Ubuntu 18.04 LTS / 20.04 LTS host has a package installed that is affected by multiple vulnerabilities as referenced in the USN-4887-1 advisory.

 - An issue was discovered in the Linux kernel before 5.11.8. 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, aka CID-f232326f6966. This affects pointer types that do not define a ptr_limit. (CVE-2020-27170)

 - An issue was discovered in the Linux kernel before 5.11.8. kernel/bpf/verifier.c has an off-by-one error (with a resultant integer underflow) affecting out-of-bounds speculation on pointer arithmetic, leading to side-channel attacks that defeat Spectre mitigations and obtain sensitive information from kernel memory, aka CID-10d2bb2e6b1d. (CVE-2020-27171)

 - An issue was discovered in the Linux kernel through 5.11.3. A kernel pointer leak can be used to determine the address of the iscsi_transport structure. When an iSCSI transport is registered with the iSCSI subsystem, the transport's handle is available to unprivileged users via the sysfs file system, at /sys/class/iscsi_transport/$TRANSPORT_NAME/handle. When read, the show_transport_handle function (in drivers/scsi/scsi_transport_iscsi.c) is called, which leaks the handle. This handle is actually the pointer to an iscsi_transport struct in the kernel module's global variables. (CVE-2021-27363)

 - An issue was discovered in the Linux kernel through 5.11.3. drivers/scsi/scsi_transport_iscsi.c is adversely affected by the ability of an unprivileged user to craft Netlink messages. (CVE-2021-27364)

 - An issue was discovered in the Linux kernel through 5.11.3. Certain iSCSI data structures do not have appropriate length constraints or checks, and can exceed the PAGE_SIZE value. An unprivileged user can send a Netlink message that is associated with iSCSI, and has a length up to the maximum length of a Netlink message. (CVE-2021-27365)

 - The bpf verifier in the Linux kernel did not properly handle mod32 destination register truncation when the source register was known to be 0. A local attacker with the ability to load bpf programs could use this gain out-of-bounds reads in kernel memory leading to information disclosure (kernel memory), and possibly out-of-bounds writes that could potentially lead to code execution. This issue was addressed in the upstream kernel in commit 9b00f1b78809 (bpf: Fix truncation handling for mod32 dst reg wrt zero) and in Linux stable kernels 5.11.2, 5.10.19, and 5.4.101. (CVE-2021-3444)

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

Solution

Update the affected kernel package.

See Also

https://ubuntu.com/security/notices/USN-4887-1

Plugin Details

Severity: High

ID: 148034

File Name: ubuntu_USN-4887-1.nasl

Version: 1.5

Type: local

Agent: unix

Published: 3/24/2021

Updated: 1/9/2024

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

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: Medium

Base Score: 4.6

Temporal Score: 3.6

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

CVSS Score Source: CVE-2021-3444

CVSS v3

Risk Factor: High

Base Score: 7.8

Temporal Score: 7

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

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

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:18.04:-:lts, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.10.0-1019-oem, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.3.0-1038-raspi2, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.3.0-1041-gke, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.3.0-72-generic, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.3.0-72-lowlatency, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1012-gkeop, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1032-raspi, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1036-kvm, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1039-gke, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1040-gcp, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1041-oracle, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1043-azure, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-70-generic, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-70-generic-lpae, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-70-lowlatency, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.6.0-1052-oem, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.8.0-48-generic, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.8.0-48-generic-64k, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.8.0-48-generic-lpae, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.8.0-48-lowlatency

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

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 3/23/2021

Vulnerability Publication Date: 3/7/2021

Reference Information

CVE: CVE-2020-27170, CVE-2020-27171, CVE-2021-27363, CVE-2021-27364, CVE-2021-27365, CVE-2021-3444

USN: 4887-1