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Gentoo: GLSA-201512-03 Normal: GRUB Auth Bypass Backspace Issue

gentoo
Calendar Grey December 19, 2015
Dist Gentoo Esm H88
The GRUB prompt allows for an evasion of authentication by using the escape key, granting unrestricted console entry. Immediate upgrade advised.
GRUB's authentication prompt can be bypassed by entering a sequence of backspace characters.

Summary

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

Topics%20covered

Topics Covered

security advisory gentoo access control authentication issue normal severity sys-boot/grub

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

[ 1 ] CVE-2015-8370 http://nvd.nist.gov/nvd.cfm?cvename=CVE-2015-8370 [ 2 ] GRUB2 Quick Start guide https://wiki.gentoo.org/wiki/GRUB2_Quick_Start

Availability

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

Severity: Normal
Title: GRUB: Authentication bypass
Date: December 19, 2015
Bugs: #568326
ID: 201512-03

Topics%20covered

Topics Covered

security advisory gentoo access control authentication issue normal severity sys-boot/grub

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.

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Affected Packages

------------------------------------------------------------------- Package / Vulnerable / Unaffected ------------------------------------------------------------------- 1 sys-boot/grub < 2.02_beta2-r8 *>= 0.97 * >= 2.02_beta2-r8 * ------------------------------------------------------------------- NOTE: Packages marked with asterisks require manual intervention!

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.

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