glsa-200402-02.xml


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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>2004-02-11</announced>
  <revised>2004-02-11: 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 &gt; 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"' &gt; 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="https://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>