Multiple Security Vulnerabilities in the Solaris X Server Extensions May lead to a Denial of Service (DoS) Condition or Allow Execution of Arbitrary Code

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Multiple Security Vulnerabilities in the Solaris X Server Extensions May Lead to a Denial of Service (DoS) Condition or Allow Execution of Arbitrary Code

1. Impact

Multiple integer, heap and buffer overflow security vulnerabilities exist in the Render, RECORD, Security, and MIT-SHM Extensions to the Solaris X11 display server (Xorg(1) and Xsun(1)) and the Solaris X11 print server (Xprt(1)).  These vulnerabilities may allow a local or remote unprivileged user who is authorized (via xhost(1) or xauth(1)) to connect to the X server and execute arbitrary code with root privileges, access arbitrary memory within the X server's address space, or crash the X11 display server process. The ability to crash the X11 display server is a type of Denial of Service (DoS).

These issues are described in the following documents:


2. Contributing Factors

These issues can occur in the following releases:

SPARC Platform

• Solaris 8 without patch 119067-10 (for Xsun(1))
• Solaris 9 without patch 112785-64 (for Xsun(1))
  
• Solaris 10 without patches 119059-44 and 125719-12
• OpenSolaris based upon builds snv_01 through snv_91
  

x86 Platform

• Solaris 8 without patch 119068-10 (for Xsun(1))
• Solaris 9 without patch 112786-53 (for Xsun(1))
• Solaris 9 without patch 118908-06 (for Xorg)
  
• Solaris 10 without patches 119060-43 and 125720-23
• OpenSolaris based upon builds snv_01 through snv_91

Notes:

1. To determine if JDS release 2 is installed on a Solaris 9 x86 system, the following command can be run:

% grep distributor-version /usr/share/gnome-about/gnome-version.xml
<distributor-version>Sun Java Desktop System, Release 2</distributor-version>

2. Only OpenSolaris installations including the affected binary "/usr/X11/bin/i386/Xorg" are impacted by this issue.

3. OpenSolaris distributions may include additional bug fixes above and beyond the base build from which it was derived.  The base build can be derived as follows:

$ uname -a
SunOS osolsys 5.11 snv_86 i86pc i386 i86pc

4. To determine if the affected X Server extensions are enabled on a running X server, the following command can be run:

$ xdpyinfo | egrep "MIT-SHM|RENDER|SECURITY|RECORD"
    MIT-SHM
    RECORD
    RENDER
    SECURITY

On Solaris 10, in the case of Xsun(1), the issues reported in CVE-2008-2360, CVE-2008-2361 and CVE-2008-2362 will not be applicable by default. They will be applicable only if the user has turned on the RENDER extension support by adding "+xrender" CLI option to Xsun, in which case the user can work around it by removing the "+xrender" option.  Also, these issues are not applicable for Xsun(1) server on Solaris 8 as the RENDER extension support is not present.

3. Symptoms

There are no predictable symptoms that would indicate these issues have been exploited to execute arbitrary code.

If any of the described issues do occur, the X server will exit and may generate an error message about a segmentation fault and may also write a core(4) file.

4. Workaround

To work around the described issues for the Xorg(1) server, the affected X Server extensions may be disabled.

The following command may be used to disable Xorg server extensions:

$ /usr/X11/bin/Xorg -extension <Name of Extension>

This change will be valid until the Xorg server is restarted, for example on logout. The command will need to be repeated for each new instance of the Xorg server.

For example, the MIT-SHM extension may be disabled as follows:

$ /usr/X11/bin/Xorg -extension MIT-SHM

The X Server extensions may also be disabled by editing the xorg.conf(4) file. For example, to disable the MIT-SHM extension, the following lines may be added to the xorg.conf(4) file:

 
Notes:

1. After disabling X Server extensions, applications requiring those extensions may not run.

2. Only certain extensions can be disabled by the user. To list all extensions that can be disabled, the following command can be run:

$ /usr/X11/bin/Xorg -extension help

For Xsun(1) server, there is no workaround to the issues described in CVE-2008-1377 and CVE-2008-1379.

To work around the issues for Xsun(1) server with Render support enabled on Solaris 10 (reported in CVE-2008-2360, CVE-2008-2361 and CVE-2008-2362) remove the "+xrender" option to Xsun.
       
On Solaris 9, there is no workaround for the issues reported in CVE-2008-2360, CVE-2008-2361 and CVE-2008-2362 for Xsun(1) server.

The documented issues can be worked around by using the "noexec_user_stack" options to defeat the most common form of buffer overflow attacks that store executable exploit code on the stack. This can be achieved by editing the "/etc/system" file and adding the lines:


A reboot will be necessary in order for the above change to take effect. See system(4) for information on modifying the system configuration information file.

5. Resolution

This issue is addressed in the following releases:

SPARC Platform

• Solaris 8 with patch 119067-10 or later (for Xsun(1))
• Solaris 9 with patch 112785-64 or later (for Xsun(1))
• Solaris 10 with patches 119059-44 or later and 125719-12 or later
• OpenSolaris based upon builds snv_92 or later
  

x86 Platform

• Solaris 8 with patch 119068-10 or later (for Xsun(1))
• Solaris 9 with patch 112786-53 or later (for Xsun(1))
• Solaris 9 with patch 118908-06 or later (for Xorg)
  
• Solaris 10 with patches 119060-43 or later and 125720-23 or later
• OpenSolaris based upon builds snv_92 or later

For more information on Security Sun Alerts, see Technical Instruction ID 213557.

This Sun Alert notification is being provided to you on an "AS IS" basis. This Sun Alert notification may contain information provided by third parties. The issues described in this Sun Alert notification may or may not impact your system(s). Sun makes no representations, warranties, or guarantees as to the information contained herein. ANY AND ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT, ARE HEREBY DISCLAIMED. BY ACCESSING THIS DOCUMENT YOU ACKNOWLEDGE THAT SUN SHALL IN NO EVENT BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, PUNITIVE, OR CONSEQUENTIAL DAMAGES THAT ARISE OUT OF YOUR USE OR FAILURE TO USE THE INFORMATION CONTAINED HEREIN. This Sun Alert notification contains Sun proprietary and confidential information. It is being provided to you pursuant to the provisions of your agreement to purchase services from Sun, or, if you do not have such an agreement, the Sun.com Terms of Use. This Sun Alert notification may only be used for the purposes contemplated by these agreements.

Copyright 2000-2008 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, CA 95054 U.S.A. All rights reserved.

Modification History

19-Jun-2008: Updated Contributing Factors, Workaround and Resolution sections
07-Jul-2008: Updated Contributing Factors and Resolution sections
29-Jul-2008: Updated Contributing Factors and Resolution sections
04-Aug-2008: Updated Contributing Factors and Resolution sections
24-Sep-2008: Updated Contributing Factors and Resolution sections
30-Sep-2008: Revised Workaround section; issue is Resolved
20-Jan-2009: Updated Contributing Factors and Resolution sections

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