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-2006-6101, CVE-2006-6102, CVE-2006-6103
(Links to External Site)
Date: Jan 10 2007
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|
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.
A local user can obtain root privileges on the target system.|
The vendor has issued a fixed version (7.2 RC3).|
Access control error, Input validation error|
|Underlying OS: Linux (Any), UNIX (Any)|
This archive entry has one or more follow-up message(s) listed below.|
Source Message Contents
Subject: iDefense Security Advisory 01.09.07: Multiple Vendor X Server Render|
Multiple Vendor X Server Render Extension ProcRenderAddGlyphs Memory
iDefense Security Advisory 01.09.07
Jan 09, 2007
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.
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.
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.
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.
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:
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
VIII. DISCLOSURE TIMELINE
12/04/2006 Initial vendor notification
12/05/2006 Initial vendor response
01/09/2007 Coordinated public disclosure
This vulnerability was discovered by Sean Larsson, iDefense Labs.
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