<table width="100%" cellpadding="2" cellspacing="0" border="0">
<tbody><tr bgcolor="#666699"><td><font size="2" color="#ffffff"><b>document id</b></font></td>
<td bgcolor="#ffffff"><font size="2"> </font></td>
<td><font size="2" color="#ffffff"><b>Synopsis</b></font></td>
<td bgcolor="#ffffff"><font size="2"> </font></td>
<td><font size="2" color="#ffffff"><b>Date</b></font></td>
</tr>
<tr bgcolor="#cccce7"><td><font size="2"><b>57619</b></font></td>
<td bgcolor="#ffffff"><font size="2"> </font></td>
<td><font size="2"><b>X Display Manager (xdm(1)) May Crash Due to Invalid XDMCP Request</b></font></td>
<td bgcolor="#ffffff"><font size="2"> </font></td>
<td><font size="2"><b>9 Aug 2004</b></font></td>
</tr>
</tbody></table><br clear="">
<table width="100%" cellpadding="2" cellspacing="0" border="0"><tbody><tr bgcolor="#999999">
<td><font size="2" color="#ffffff"><b><a name="Description">Description</a></b></font></td>
<td align="right"><b><a href="#top"><font size="2" color="#ffffff">Top</font></a></b></td></tr></tbody></table>
<font size="2"><h2>
        Sun(sm) Alert Notification
      </h2><ul>
        <li>
          Sun Alert ID: 57619
        </li>
        <li>
          Synopsis: X Display Manager (xdm(1)) May Crash Due to Invalid XDMCP Request
        </li>
        <li>
          Category: Security
        </li>
        <li>
          Product: Solaris
        </li>
        <li>
          BugIDs: 5023755
        </li>
        <li>
          Avoidance: Workaround, Patch
        </li>
        <li>
          State: Engineering Complete
        </li>
        <li>
          Date Released: 09-Aug-2004
        </li>
        <li>
          Date Closed:
        </li>
        <li>
          Date Modified:
        </li>
      </ul><h2>
        1. Impact
      </h2><p>
A remote unprivileged user may be able to crash the X Display Manager
(xdm(1)) when using an invalid X Display Manager Control Protocol
(XDMCP) request, thus causing a Denial of Service (DoS). </p><h2>
        2. Contributing Factors
      </h2><p>
        This issue can occur in the following releases:
      </p><p>
        <b>SPARC Platform</b>
      </p><ul>
        <li>
          Solaris 7
        </li>
        <li>
          Solaris 8
        </li>
        <li>
          Solaris 9 without patch <a href="http://sunsolve.sun.com/pub-cgi/findPatch.pl?patchId=112785&rev=38">112785-38</a>
        </li>
      </ul><p>
        <b>x86 Platform</b>
      </p><ul>
        <li>
          Solaris 7
        </li>
        <li>
          Solaris 8
        </li>
        <li>
          Solaris 9 without patch <a href="http://sunsolve.sun.com/pub-cgi/findPatch.pl?patchId=112786&rev=27">112786-27</a>
        </li>
      </ul><h2>
        3. Symptoms
      </h2><p>
        If the described issue occurs, the X Display Manager will exit without warning.
      </p></font><table width="100%" cellpadding="2" cellspacing="0" border="0"><tbody><tr bgcolor="#999999">
<td><font size="2" color="#ffffff"><b><a name="Solution-Summary">Solution Summary</a></b></font></td>
<td align="right"><b><a href="#top"><font size="2" color="#ffffff">Top</font></a></b></td></tr></tbody></table>
<font size="2"><h2>
        4. Relief/Workaround
      </h2><p> To
reduce the possibility of the described issue from occurring, network
administrators should block UDP(7P) packets to port 177 across any
firewall where XDMCP remote session service is not required. </p><p> If XDMCP remote session access to a machine is not
required at all, but graphical login access via xdm(1M) for console
devices is required, xdm(1M) can be configured to not listen for XDMCP
connections by editing the "/usr/openwin/lib/X11/xdm/xdm-config" file
and adding the following line: </p><pre>    DisplayManager.requestPort: 0                        </pre><p>
        <b>Note: </b>Controlling access via the access control list in the "Xaccess" file is not effective at preventing this issue.
      </p><h2>
        5. Resolution
      </h2><p>
        This issue is addressed in the following releases:
      </p><p>
        <b>SPARC Platform</b>
      </p><ul>
        <li>
          Solaris 9 with patch <a href="http://sunsolve.sun.com/pub-cgi/findPatch.pl?patchId=112785&rev=34">112785-34</a> or later
        </li>
      </ul><p>
        <b>x86 Platform</b>
      </p><ul>
        <li>
          Solaris 9 with patch <a href="http://sunsolve.sun.com/pub-cgi/findPatch.pl?patchId=112786&rev=27">112786-27</a> or later
        </li>
      </ul><p>
        A final resolution is pending completion.
      </p><p>
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      </p><p>
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