[RndTbl] [New security bug:] X.Org: Screen lock bypass

[Adam Thompson]

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 at athompso.net


> -----Original Message-----
> From: Alex Legler [mailto:a3li at gentoo.org]
> Sent: Friday, January 27, 2012 4:00 PM
> To: gentoo-announce at lists.gentoo.org
> Cc: bugtraq at securityfocus.com; full-disclosure at lists.grok.org.uk;
> security-alerts at 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
> =================
>
>     ----------------------------------------------------------------
> ---
>      Package              /     Vulnerable     /
> Unaffected
>     ----------------------------------------------------------------
> ---
>   1  x11-misc/xkeyboard-config
>                                  < 2.4.1-r3               >= 2.4.1-
> r3
>     ----------------------------------------------------------------
> ---
>      # 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 at 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