Public Vulnerability Reports

Multiple Vendor X Server XInput Extension Multiple Memory Corruption Vulnerabilities

17.01.08

BACKGROUND

The X Window System (or X11) is a graphical windowing system used on Unix-like systems. It is based on a client/server model. More information about about The X Window system is available at the following URL.

http://en.wikipedia.org/wiki/X_Window_System

DESCRIPTION

Local exploitation of multiple memory corruption vulnerabilities in the X.Org X server, as included in various vendors' operating system distributions, allows attackers to execute arbitrary code with the privileges of the X server, typically root.

Vulnerable code exists within multiple functions in the XInput extension. By sending specially crafted X11 requests, an attacker is able to corrupt heap memory located after their request data. This results in a potentially exploitable condition.

ANALYSIS

Exploitation allows an attacker to execute arbitrary code with root privileges. In order to exploit these vulnerabilities, an attacker must be able to send commands to an affected X server. This typically requires access to the console or access to the same account as a user who is on the console.

If an X Server is configured to listen for TCP based client connections, and a client is granted access to create sessions (via the xhosts file), then these vulnerabilities can be exploited remotely.

DETECTION

iDefense has confirmed the existence of these vulnerabilities in X.Org X11 version R7.3. Previous versions may also be affected.

WORKAROUND

iDefense is currently unaware of any workarounds for this issue. The XInput extension is normally compiled into the X Server; as such, it's not possible to disable it from being loaded in the configuration file.

VENDOR RESPONSE

The X.Org team has addressed these vulnerabilities with the release of Xserver version 1.4.1. Additionally, patches for versions 1.4 and 1.2 have been made available. For more information, consult the X.Org advisory at the following URL.

http://lists.freedesktop.org/archives/xorg/2008-January/031918.html

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2007-6427 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org/), which standardizes names for security problems.

DISCLOSURE TIMELINE

11/29/2007 Initial vendor notification
12/04/2007 Initial vendor response
01/17/2008 Coordinated public disclosure

CREDIT

These vulnerabilities were reported to VeriSign iDefense by regenrecht.

Get paid for vulnerability research
http://labs.idefense.com/methodology/vulnerability/vcp.php

Free tools, research and upcoming events
http://labs.idefense.com/

LEGAL NOTICES

Copyright © 2008 Verisign, Inc.

Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDefense. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please e-mail customer service for permission.

Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.