Ubuntu: 4992-1 Critical: GRUB 2 Bootloader Security Flaws

ubuntu

June 18, 2021

Several security issues were fixed in GRUB 2.

Summary

Several security issues were fixed in GRUB 2.

Software Description:

- grub2-signed: GRand Unified Bootloader

- grub2-unsigned: GRand Unified Bootloader

Details:

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. (CVE-2020-14372)

Chris Coulson discovered that the rmmod command in GRUB 2 contained a use-after-free vulnerability. A local attacker could use this to execute

arbitrary code and bypass UEFI Secure Boot restrictions. (CVE-2020-25632)

Chris Coulson discovered that a buffer overflow existed in the command line

parser in GRUB 2. A local attacker could use this to execute arbitrary code

and bypass UEFI Secure Boot restrictions. (CVE-2020-27749)

It was discovered that the cutmem command in GRUB 2 did not honor secure

boot locking. A local attacker could use this to execute arbitrary code and

bypass ...

Read the Full Advisory

Topics Covered

security advisory security issue update critical Ubuntu bootloader GRUB 2

Update Instructions

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 20.10:
  grub-efi-amd64-bin              2.04-1ubuntu44.2
  grub-efi-amd64-signed           1.167.2+2.04-1ubuntu44.2
  grub-efi-arm64-bin              2.04-1ubuntu44.2
  grub-efi-arm64-signed           1.167.2+2.04-1ubuntu44.2

Ubuntu 20.04 LTS:
  grub-efi-amd64-bin              2.04-1ubuntu44.2
  grub-efi-amd64-signed           1.167.2+2.04-1ubuntu44.2
  grub-efi-arm64-bin              2.04-1ubuntu44.2
  grub-efi-arm64-signed           1.167.2+2.04-1ubuntu44.2

Ubuntu 18.04 LTS:
  grub-efi-amd64-bin              2.04-1ubuntu44.1.2
  grub-efi-amd64-signed           1.167~18.04.5+2.04-1ubuntu44.1.2
  grub-efi-arm64-bin              2.04-1ubuntu44.1.2
  grub-efi-arm64-signed           1.167~18.04.5+2.04-1ubuntu44.1.2

After a standard system update you need to reboot your computer to make
all the necessary changes.