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<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE glsa SYSTEM "http://www.gentoo.org/dtd/glsa.dtd">
<glsa id="200402-02">
<title>XFree86 Font Information File Buffer Overflow</title>
<synopsis>
Exploitation of a buffer overflow in the XFree86 Project Inc.'s XFree86 X
Window System allows local attackers to gain root privileges.
</synopsis>
<product type="ebuild">200402-02</product>
<announced>February 11, 2004</announced>
<revised>February 11, 2004: 01</revised>
<access>local</access>
<affected>
<package name="x11-base/xfree" auto="yes" arch="*">
<vulnerable range="lt">4.3.99.902-r1</vulnerable>
<unaffected range="eq">4.2.1-r3</unaffected>
<unaffected range="eq">4.3.0-r4</unaffected>
<unaffected range="ge">4.3.99.902-r1</unaffected>
</package>
</affected>
<background>
<p>
XFree86, provides a client/server interface between display
hardware and the desktop environment while also providing both the
windowing infrastructure and a standardized API. XFree86 is
platform independent, network-transparent and extensible.
</p>
</background>
<description>
<p>
Exploitation of a buffer overflow in The XFree86 Window System
discovered by iDefence allows local attackers to gain root
privileges.
</p>
<p>
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.
</p>
<p>
To reproduce the overflow on the command line one can run:
</p>
<code>
# cat > fonts.dir &lt;&lt;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</code>
<p>
{Some output removed}... Server aborting... Segmentation fault (core dumped)
</p>
</description>
<impact type="high">
<p>
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.
</p>
</impact>
<workaround>
<p>
No immediate workaround is available; a software upgrade is required.
</p>
<p>
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.
</p>
</workaround>
<resolution>
<p>
All users are recommended to upgrade their XFree86 installation:
</p>
<code>
# emerge sync
# emerge -pv x11-base/xfree
# emerge x11-base/xfree</code>
</resolution>
<references>
<uri
link="http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2004-0083">CVE: CAN-2004-0083</uri>
<uri link="http://www.idefense.com/application/poi/display?id=72&amp;type=vulnerabilities">Vulnerability:
XFree86 Font Information File Buffer Overflow</uri>
</references>
</glsa>