CVE-2020-14372
Publication date 2 March 2021
Last updated 24 July 2024
Ubuntu priority
Cvss 3 Severity Score
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.
Status
Package | Ubuntu Release | Status |
---|---|---|
grub2 | 24.10 oracular |
Not affected
|
24.04 LTS noble |
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
|
|
22.04 LTS jammy |
Not affected
|
|
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 | Ignored end of ESM support, was needed | |
grub2-unsigned | 24.10 oracular |
Not affected
|
24.04 LTS noble |
Not affected
|
|
22.04 LTS jammy |
Not affected
|
|
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)
- USN-4992-1
- GRUB 2 vulnerabilities
- 18 June 2021