GLSA-200402-02 : XFree86 Font Information File Buffer Overflow

This script is Copyright (C) 2004-2014 Tenable Network Security, Inc.


Synopsis :

The remote Gentoo host is missing one or more security-related
patches.

Description :

The remote host is affected by the vulnerability described in GLSA-200402-02
(XFree86 Font Information File Buffer Overflow)

Exploitation of a buffer overflow in The XFree86 Window System
discovered by iDefence allows local attackers to gain root
privileges.
The problem exists in the parsing of the 'font.alias' file. The X
server (running as root) fails to check the length of the user
provided input, so a malicious user may craft a malformed
'font.alias' file causing a buffer overflow upon parsing,
eventually leading to the execution of arbitrary code.
To reproduce the overflow on the command line one can run:
# cat > fonts.dir <<EOF
1
word.bdf -misc-fixed-medium-r-semicondensed--13-120-75-75-c-60-iso8859-1
EOF
# perl -e 'print '0' x 1024 . 'A' x 96 . '\\n'' > fonts.alias
# X :0 -fp $PWD
{Some output removed}... Server aborting... Segmentation fault (core dumped)

Impact :

Successful exploitation can lead to a root compromise provided
that the attacker is able to execute commands in the X11
subsystem. This can be done either by having console access to the
target or through a remote exploit against any X client program
such as a web-browser, mail-reader or game.

Workaround :

No immediate workaround is available
a software upgrade is required.
Gentoo has released XFree 4.2.1-r3, 4.3.0-r4 and 4.3.99.902-r1 and
encourages all users to upgrade their XFree86
installations. Vulnerable versions are no longer available in
Portage.

See also :

http://www.nessus.org/u?e8ff1873
http://www.gentoo.org/security/en/glsa/glsa-200402-02.xml

Solution :

All users are recommended to upgrade their XFree86 installation:
# emerge sync
# emerge -pv x11-base/xfree
# emerge x11-base/xfree

Risk factor :

Critical / CVSS Base Score : 10.0
(CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C)

Family: Gentoo Local Security Checks

Nessus Plugin ID: 14446 (gentoo_GLSA-200402-02.nasl)

Bugtraq ID:

CVE ID: CVE-2004-0083