X.Org X server: Multiple vulnerabilities

Security Team Contact Address

Updated June 19, 2008

1. Gentoo Linux Security Advisory

Advisory Reference	GLSA 200806-07 / xorg-server
Release Date	June 19, 2008
Latest Revision	June 19, 2008: 01
Impact	high
Exploitable	remote, local

Package	Vulnerable versions	Unaffected versions	Architecture(s)
x11-base/xorg-server	< 1.3.0.0-r6	>= 1.3.0.0-r6	All supported architectures

Related bugreports: #225419

Synopsis

Multiple vulnerabilities have been discovered in the X.Org X server, possibly allowing for the remote execution of arbitrary code with root privileges.

2. Impact Information

Background

The X Window System is a graphical windowing system based on a client/server model.

Description

Regenrecht reported multiple vulnerabilities in various X server extensions via iDefense:

The SProcSecurityGenerateAuthorization() and SProcRecordCreateContext() functions of the RECORD and Security extensions are lacking proper parameter validation (CVE-2008-1377).
An integer overflow is possible in the function ShmPutImage() of the MIT-SHM extension (CVE-2008-1379).
The RENDER extension contains several possible integer overflows in the AllocateGlyph() function (CVE-2008-2360) which could possibly lead to a heap-based buffer overflow. Further possible integer overflows have been found in the ProcRenderCreateCursor() function (CVE-2008-2361) as well as in the SProcRenderCreateLinearGradient(), SProcRenderCreateRadialGradient() and SProcRenderCreateConicalGradient() functions (CVE-2008-2362).

Impact

Exploitation of these vulnerabilities could possibly lead to the remote execution of arbitrary code with root privileges, if the server is running as root, which is the default. It is also possible to crash the server by making use of these vulnerabilities.

3. Resolution Information

Workaround

It is possible to avoid these vulnerabilities by disabling the affected server extensions. Therefore edit the configuration file (/etc/X11/xorg.conf) to contain the following in the appropriate places:

Code Listing 3.1: Workaround

  Section "Extensions"   
	Option "MIT-SHM" "disable"
	Option "RENDER" "disable" 
	Option "SECURITY" "disable"
  EndSection

  Section "Module"
   Disable "record"
  EndSection

Resolution

All X.org X Server users should upgrade to the latest version:

Code Listing 3.2: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=x11-base/xorg-server-1.3.0.0-r6"

4. References