X.Org X server and Xfont library: Multiple vulnerabilities

Security Team Contact Address

Updated January 20, 2008

1. Gentoo Linux Security Advisory

Advisory Reference	GLSA 200801-09 / xorg-server libXfont
Release Date	January 20, 2008
Latest Revision	March 05, 2008: 03
Impact	high
Exploitable	remote, local

Package	Vulnerable versions	Unaffected versions	Architecture(s)
x11-base/xorg-server	< 1.3.0.0-r5	>= 1.3.0.0-r5	All supported architectures
x11-libs/libXfont	< 1.3.1-r1	>= 1.3.1-r1	All supported architectures

Related bugreports: #204362, #208343

Synopsis

Multiple vulnerabilities have been discovered in the X.Org X server and Xfont library, allowing for a local privilege escalation and arbitrary code execution.

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 extension via iDefense:

The XFree86-Misc extension does not properly sanitize a parameter within a PassMessage request, allowing the modification of a function pointer (CVE-2007-5760).
Multiple functions in the XInput extension do not properly sanitize client requests for swapping bytes, leading to corruption of heap memory (CVE-2007-6427).
Integer overflow vulnerabilities in the EVI extension and in the MIT-SHM extension can lead to buffer overflows (CVE-2007-6429).
The TOG-CUP extension does not sanitize an index value in the ProcGetReservedColormapEntries() function, leading to arbitrary memory access (CVE-2007-6428).
A buffer overflow was discovered in the Xfont library when processing PCF font files (CVE-2008-0006).
The X server does not enforce restrictions when a user specifies a security policy file and attempts to open it (CVE-2007-5958).

Impact

Remote attackers could exploit the vulnerability in the Xfont library by enticing a user to load a specially crafted PCF font file resulting in the execution of arbitrary code with the privileges of the user running the X server, typically root. Local attackers could exploit this and the vulnerabilities in the X.org extensions to gain elevated privileges. If the X server allows connections from the network, these vulnerabilities could be exploited remotely. A local attacker could determine the existence of arbitrary files by exploiting the last vulnerability or possibly cause a Denial of Service.

3. Resolution Information

Workaround

Workarounds for some of the vulnerabilities can be found in the X.Org security advisory as listed under References.

Resolution

All X.Org X server users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=x11-base/xorg-server-1.3.0.0-r5"

All X.Org Xfont library users should upgrade to the latest version:

Code Listing 3.2: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=x11-libs/libXfont-1.3.1-r1"

4. References