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Category:   Application (Generic)  >   X Vendors:   X.org
X Memory Corruption Errors in Render and DBE Extensions Let Local Users Gain Root Privileges
SecurityTracker Alert ID:  1017495
SecurityTracker URL:  http://securitytracker.com/id/1017495
CVE Reference:   CVE-2006-6101, CVE-2006-6102, CVE-2006-6103   (Links to External Site)
Date:  Jan 10 2007
Impact:   Execution of arbitrary code via local system, Root access via local system
Fix Available:  Yes  Vendor Confirmed:  Yes  
Version(s): 7.1-1.1.0, possibly other versions
Description:   Several vulnerabilities were reported in X. A local user can obtain root privileges on the target system.

A local user with the ability to send commands to an affected X server can trigger a memory corruption error in the ProcRenderAddGlyphs() function of the Render extension to execute arbitrary commands on the target system, typically with root privileges [CVE-2006-6101].

A memory corruption error also resides in the ProcDbeGetVisualInfo() function of the DBE extension [CVE-2006-6102].

A memory corruption error also resides in the ProcDbeSwapBuffers() function of the DBE extension [CVE-2006-6103].

The vendor was notified on December 4, 2006.

The XFree86 X server is also affected by these vulnerabilities.

Sean Larsson of iDefense Labs discovered these vulnerability.

Impact:   A local user can obtain root privileges on the target system.
Solution:   The vendor has issued a fixed version (7.2 RC3).
Cause:   Access control error, Input validation error
Underlying OS:  Linux (Any), UNIX (Any)

Message History:   This archive entry has one or more follow-up message(s) listed below.
Jan 10 2007 (Red Hat Issues Fix) X Memory Corruption Errors in Render and DBE Extensions Let Local Users Gain Root Privileges
Red Hat has released a fix for Red Hat Enterprise Linux 4.
Jan 10 2007 (Red Hat Issues Fix for XFree86) X Memory Corruption Errors in Render and DBE Extensions Let Local Users Gain Root Privileges
Red Hat has released a fix for XFree86 for Red Hat Enterprise Linux 2.1 and 3.
Feb 16 2007 (Sun Issues Fix) X Memory Corruption Errors in Render and DBE Extensions Let Local Users Gain Root Privileges
Sun has issued a fix for Solaris 8.
Mar 9 2007 (NetBSD Issues Fix) X Memory Corruption Errors in Render and DBE Extensions Let Local Users Gain Root Privileges
NetBSD has released a fix.
Jun 22 2007 (HP Issues Fix for HP-UX) X Memory Corruption Errors in Render and DBE Extensions Let Local Users Gain Root Privileges
HP issues fix for HP-UX 11.11, 11.21, and 11.31.



 Source Message Contents

Subject:  iDefense Security Advisory 01.09.07: Multiple Vendor X Server Render

Multiple Vendor X Server Render Extension ProcRenderAddGlyphs Memory
Corruption Vulnerability

iDefense Security Advisory 01.09.07
http://labs.idefense.com/intelligence/vulnerabilities/
Jan 09, 2007

I. BACKGROUND

The X Window System is a graphical windowing system based on a
client/server model. More information about about The X Window system is
available at the following links.

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

II. DESCRIPTION

Local exploitation of a memory corruption vulnerability in the
"ProcRenderAddGlyphs" function in the X.Org and XFree86 X server could
allow an attacker to execute arbitrary code with privileges of the X
server, typically root.

This vulnerability specifically lies within the Render extension.
Insufficient input validation exists when allocating memory for glyph
management data structures. By sending a specially crafted X protocol
request to the Render extension, an attacker can cause an exploitable
memory corruption condition.

III. ANALYSIS

Successful exploitation allows an attacker to execute arbitrary as the root
user. In order to exploit this vulnerability an attacker would require the
ability 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. One method of gaining the required access would be to
remotely exploit a vulnerability in, for example, a graphical web browser.
This would then allow an attacker to exploit this vulnerability and elevate
their privileges to root.

IV. DETECTION

iDefense has confirmed the existence of this vulnerability in the X.Org
server version 7.1-1.1.0. Previous versions may also be affected.

V. WORKAROUND

Access to the vulnerable code can be prevented when the Render extension is
not built into the X binary. This can be accomplished by removing the entry
for the Render extension from your X server's configuration file, often
stored in /etc/X11 and named xorg.conf or XF86Config-4. To do this, remove
the following line from the 'Module' section:

Load "render"

This will prevent the Render extension from loading, which may affect the
appearance or operation of some applications.

VI. VENDOR RESPONSE

The X.Org foundation has addressed this vulnerability within version 7.2
RC3 of X.Org's X server. Additionally, patches have been made available
for older releases.

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CVE-2006-6101 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
security problems.

VIII. DISCLOSURE TIMELINE

12/04/2006  Initial vendor notification
12/05/2006  Initial vendor response
01/09/2007  Coordinated public disclosure

IX. CREDIT

This vulnerability was discovered by Sean Larsson, iDefense Labs.

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

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

X. LEGAL NOTICES


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
customerservice@idefense.com 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.

_______________________________________________
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http://www.idefense.com/mailman/listinfo/idlabs-advisories
 
 


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