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USN-868-1: GRUB 2 vulnerability

9 December 2009

GRUB 2 vulnerability




It was discovered that GRUB 2 did not properly validate passwords. An
attacker with physical access could conduct a brute force attack and bypass
authentication by submitting a 1 character password.

Update instructions

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

Ubuntu 9.10

In general, a standard system upgrade is sufficient to effect the
necessary changes.

Users who have upgraded from GRUB Legacy to GRUB 2 and did not run
'upgrade-from-grub-legacy' (ie those who are still using Grub Legacy to
chainload into GRUB 2) will have to run the following command (possibly
adjusting 'hd0') to update GRUB 2's on disk core image:

$ sudo grub-install --no-floppy --grub-setup=/bin/true "(hd0)"