GLSA 201201-16: X.Org X Server/X Keyboard Configuration Database: Screen lock bypass

http://security.gentoo.org/

Severity:	normal
Title:	X.Org X Server/X Keyboard Configuration Database: Screen lock bypass
Date:	01/27/2012
Bugs:	#399347
ID:	201201-16

Synopsis

A debugging functionality in the X.Org X Server that is bound to a hotkey by default can be used by local attackers to circumvent screen locking utilities.

Background

The X Keyboard Configuration Database provides keyboard configuration for various X server implementations.

Affected packages

Package	Vulnerable	Unaffected	Architecture(s)
x11-misc/xkeyboard-config	< 2.4.1-r3	>= 2.4.1-r3	amd64, arm, hppa, x86

Description

Starting with the =x11-base/xorg-server-1.11 package, the X.Org X Server again provides debugging functionality that can be used terminate an application that exclusively grabs mouse and keyboard input, like screen locking utilities.

Gu1 reported that the X Keyboard Configuration Database maps this functionality by default to the Ctrl+Alt+Numpad * key combination.

Impact

A physically proximate attacker could exploit this vulnerability to gain access to a locked X session without providing the correct credentials.

Workaround

Downgrade to any version of x11-base/xorg-server below x11-base/xorg-server-1.11:

      # emerge --oneshot --verbose "<x11-base/xorg-server-1.11"

Resolution

All xkeyboard-config users should upgrade to the latest version:

      # emerge --sync
      # emerge --ask --oneshot --verbose
      ">=x11-misc/xkeyboard-config-2.4.1-r3"

NOTE: The X.Org X Server 1.11 was only stable on the AMD64, ARM, HPPA, and x86 architectures. Users of the stable branches of all other architectures are not affected and will be directly provided with a fixed X Keyboard Configuration Database version.

References

CVE-2012-0064

Availability

This GLSA and any updates to it are available for viewing at the Gentoo Security Website: http://security.gentoo.org/glsa/glsa-201201-16.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.