GLSA 201512-03: GRUB: Authentication bypass

http://security.gentoo.org/

Severity:	normal
Title:	GRUB: Authentication bypass
Date:	12/19/2015
Bugs:	#568326
ID:	201512-03

Synopsis

GRUB's authentication prompt can be bypassed by entering a sequence of backspace characters.

Background

GNU GRUB is a multiboot boot loader used by most Linux systems.

Affected packages

Package	Vulnerable	Unaffected	Architecture(s)
sys-boot/grub	< 2.02_beta2-r8	>= 2.02_beta2-r8	All supported architectures

Description

An integer underflow in GRUB’s username/password authentication code has been discovered.

Impact

An attacker with access to the system console may bypass the username prompt by entering a sequence of backspace characters, allowing them e.g. to get full access to GRUB’s console or to load a customized kernel.

Workaround

There is no known workaround at this time.

Resolution

All GRUB 2.x users should upgrade to the latest version:

      # emerge --sync
      # emerge --ask --oneshot --verbose ">=sys-boot/grub-2.02_beta2-r8"

After upgrading, make sure to run the grub2-install command with options appropriate for your system. See the GRUB2 Quick Start guide in the references below for examples. Your system will be vulnerable until this action is performed.

References

Availability

This GLSA and any updates to it are available for viewing at the Gentoo Security Website: http://security.gentoo.org/glsa/glsa-201512-03.xml

Concerns?

Security is a primary focus of Gentoo Linux and ensuring the confidentiality and security of our users machines is of utmost importance to us. Any security concerns should be addressed to security@gentoo.org or alternatively, you may file a bug at https://bugs.gentoo.org.