CVE-2020-14372

Publication date 2 March 2021

Last updated 24 July 2024

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

7.5 · High

Score breakdown

A flaw was found in grub2 in versions prior to 2.06, where it incorrectly enables the usage of the ACPI command when Secure Boot is enabled. This flaw allows an attacker with privileged access to craft a Secondary System Description Table (SSDT) containing code to overwrite the Linux kernel lockdown variable content directly into memory. The table is further loaded and executed by the kernel, defeating its Secure Boot lockdown and allowing the attacker to load unsigned code. The highest threat from this vulnerability is to data confidentiality and integrity, as well as system availability.

From the Ubuntu Security Team

Máté Kukri discovered that the acpi command in GRUB 2 allowed privileged users to load crafted ACPI tables when secure boot is enabled. An attacker could use this to bypass UEFI Secure Boot restrictions.

Read the notes from the security team

Status

Package Ubuntu Release Status
grub2 24.10 oracular
Not affected
24.04 LTS noble
Not affected
23.10 mantic
Not affected
23.04 lunar
Not affected
22.10 kinetic
Not affected
22.04 LTS jammy
Not affected
20.04 LTS focal
Not affected
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty
Not affected
grub2-signed 24.10 oracular
Not affected
24.04 LTS noble
Not affected
23.10 mantic
Not affected
23.04 lunar
Not affected
22.10 kinetic
Not affected
22.04 LTS jammy
Not affected
21.10 impish
Fixed 1.169
21.04 hirsute
Fixed 1.164
20.10 groovy
Fixed 1.167.2
20.04 LTS focal
Fixed 1.167.2
18.04 LTS bionic
Fixed 1.167~18.04.5
16.04 LTS xenial
Fixed 1.164
14.04 LTS trusty
Vulnerable
grub2-unsigned 24.10 oracular
Not affected
24.04 LTS noble
Not affected
23.10 mantic
Not affected
23.04 lunar
Not affected
22.10 kinetic
Not affected
22.04 LTS jammy
Not affected
21.10 impish
Fixed 2.04-1ubuntu45
21.04 hirsute
Fixed 2.04-1ubuntu42
20.10 groovy
Fixed 2.04-1ubuntu44.2
20.04 LTS focal
Fixed 2.04-1ubuntu44.2
18.04 LTS bionic
Fixed 2.04-1ubuntu44.1.2
16.04 LTS xenial
Fixed 2.04-1ubuntu42
14.04 LTS trusty Not in release

Notes

alexmurray

CVE title: "grub2: acpi command allows privileged user to load crafted ACPI tables when secure boot is enabled"

sbeattie

grub2-unsigned will contain fixes and supersede grub2, which will contain only BIOS grub bits.

Severity score breakdown

Parameter Value
Base score 7.5 · High
Attack vector Local
Attack complexity High
Privileges required High
User interaction None
Scope Changed
Confidentiality High
Integrity impact High
Availability impact High
Vector CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H

References

Related Ubuntu Security Notices (USN)

Other references