Of interest to anyone running X workstations outside physically secure environments (like their basements), I should think.

This announcement is from Gentoo, since everyone else appears to have embargoed their information on this temporarily. (Which in turn suggests that a major vendor is vulnerable and hasn't patched it yet.)

This should only affect recent distros (e.g. Fedora 16, but not 15). There's a workaround suggested in Red Hat bugzilla #783039.

Best information I can find about it until MITRE releases the CVE: http://who-t.blogspot.com/2012/01/xkb-breaking-grabs-cve-2012-0064.html.

Happy patching,

-Adam Thompson athompso@athompso.net

-----Original Message----- From: Alex Legler [mailto:a3li@gentoo.org] Sent: Friday, January 27, 2012 4:00 PM To: gentoo-announce@lists.gentoo.org Cc: bugtraq@securityfocus.com; full-disclosure@lists.grok.org.uk; security-alerts@linuxsecurity.com Subject: [gentoo-announce] [ GLSA 201201-16 ] X.Org X Server/X Keyboard Configuration Database: Screen lock bypass

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Gentoo Linux Security Advisory GLSA 201201-16

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http://security.gentoo.org/

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

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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

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 Package              /     Vulnerable     /

Unaffected

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1 x11-misc/xkeyboard-config < 2.4.1-r3 >= 2.4.1- r3 ----------------------------------------------------------------

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 # Package 1 only applies to users of these architectures:
   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 -v ">=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

[ 1 ] CVE-2012-0064 http://nvd.nist.gov/nvd.cfm?cvename=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.

License

Copyright 2012 Gentoo Foundation, Inc; referenced text belongs to its owner(s).

The contents of this document are licensed under the Creative Commons - Attribution / Share Alike license.

http://creativecommons.org/licenses/by-sa/2.5