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Original release date: June 19, 2001<BR>
Last revised: January 17, 2002<BR>
Source: CERT/CC<BR>

<P>A complete revision history is at the end of this file.

<A NAME="affected">
<H3>Systems Affected</H3>
<ul>
<li>Systems running Microsoft Windows NT 4.0 with IIS 4.0 or IIS 5.0 enabled</li>
<li>Systems running Microsoft Windows 2000 (Professional, Server, Advanced Server, Datacenter Server)</li>
<li>Systems running beta versions of Microsoft Windows XP
</ul>

<A NAME="overview">
<H2>Overview</H2>

<P>A vulnerability exists in the Indexing Services used by Microsoft
IIS 4.0 and IIS 5.0 running on Windows NT, Windows 2000, and beta
versions of Windows XP. This vulnerability allows a remote intruder to
run arbitrary code on the victim machine.

<P>Since specific technical details on how to create an exploit are
publicly available for this vulnerability, system administrators
should apply fixes or workarounds on affected systems as soon as
possible.

<p>A translation of this advisory into Polish is available at <a href="http://www.cert.pl/CA/CA-2001-13-PL.html">http://www.cert.pl/CA/CA-2001-13-PL.html</a>.

</P>
 
<P>
<A NAME="description">
<H2>I. Description</H2>

<P>There is a remotely exploitable buffer overflow in one of the ISAPI
extensions installed with most versions of IIS 4.0 and 5.0 (The
specific Internet/Indexing Service Application Programming Interface
extension is IDQ.DLL). An intruder exploiting this vulnerability may
be able to execute arbitrary code in the Local System security
context. This essentially can give the attacker complete control of
the victim system.

<P>This vulnerability was discovered by eEye Digital Security.
Microsoft has released the following bulletin regarding this issue:

<DL><DD>
<A HREF="http://www.microsoft.com/technet/security/bulletin/MS01-033.asp">http://www.microsoft.com/technet/security/bulletin/MS01-033.asp</A>
</DL>

<P>Affected versions of Windows include Windows NT 4.0 (installed with
IIS 4.0 and Index Server 2.0), Windows 2000 (Server and Professional
with IIS 5.0 installed), and Windows 2000 Datacenter Server OEM
distributions; however, not all of these instances are vulnerable by
default. The beta versions of Windows XP are vulnerable by default.

<P>The only precondition for exploiting this vulnerability is that an
IIS server is running with script mappings for Internet Data
Administration (.ida) and Internet Data Query (.idq) files. The
Indexing Services do not need to be running. As stated by Microsoft in
MS01-033:

<FONT FACE="monospace">
<PRE><DL>
   The buffer overrun occurs before any indexing functionality is
   requested. As a result, even though idq.dll is a component of Index
   Server/Indexing Service, the service would not need to be running
   in order for an attacker to exploit the vulnerability. As long as
   the script mapping for .idq or .ida files were present, and the
   attacker were able to establish a web session, he could exploit the
   vulnerability.
</DL></PRE></FONT>

<P>This vulnerability has been assigned the identifier CAN-2001-0500 by
the Common Vulnerabilities and Exposures (CVE) group:

<dl>
<dd><A
HREF="http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2001-0500">http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2001-0500</a>
</dd>
</dl>
</P>


<A NAME="impact">
<H2>II. Impact</H2>

<P>
Anyone who can reach a vulnerable web server can execute arbitrary
code in the Local System security context. This results in the
intruder gaining complete control of the system. Note that this may be
significantly more serious than a simple "web defacement."

</P>

<A NAME="solution">
<H2>III. Solution</H2>

<H4>Apply a patch from your vendor</H4>

<P>
Apply patches for vulnerable Windows NT 4.0 and Windows 2000 systems:
<P>
For Windows NT 4.0:<BR>
<DL><DD>
<A HREF="http://www.microsoft.com/Downloads/Release.asp?ReleaseID=30833">http://www.microsoft.com/Downloads/Release.asp?ReleaseID=30833</A>
</DL>
<BR>For Windows 2000 Professional, Server, and Advanced Server:<BR>
<DL><DD>
<A HREF="http://www.microsoft.com/Downloads/Release.asp?ReleaseID=30800">http://www.microsoft.com/Downloads/Release.asp?ReleaseID=30800</A>
<A HREF="http://www.microsoft.com/Downloads/Release.asp?ReleaseID=30800"></A>
</DL>


<P>Users of Windows 2000 Datacenter Server software should contact
their original equipment manufacturer (OEM) for patches. A list of OEM
providers may be found here:<BR>

<DL><DD>
<a href="http://www.microsoft.com/windows2000/datacenter/howtobuy/purchasing/oems.asp">http://www.microsoft.com/windows2000/datacenter/howtobuy/purchasing/oems.asp</a>
</DL>

<H4>Workarounds</H4>

<P>
Users of beta copies of Windows XP should upgrade to a newer version
of the software when it becomes available.

<P>All affected versions of IIS/Indexing Services can be protected
against exploits of this vulnerability by removing script mappings for Internet Data Administration (.ida) and Internet Data Query (.idq)
files. However, such mappings may be recreated when installing other related
software components.

<A NAME="vendors">
<H2>Appendix A. Vendor Information</H2>

<A name="microsoft">
<H3>Microsoft Corporation</H3>
<P>
The following documents regarding this vulnerability are available
from Microsoft:<BR>

<DL><DD>
<A HREF="http://www.microsoft.com/technet/security/bulletin/MS01-033.asp">http://www.microsoft.com/technet/security/bulletin/MS01-033.asp</A>
</DL>
<DD>
<A HREF="http://www.microsoft.com/technet/security/bulletin/MS01-044.asp">http://www.microsoft.com/technet/security/bulletin/MS01-044.asp</A>
</DL>
<DL><DD>
<a href="http://www.microsoft.com/technet/support/kb.asp?ID=Q300972">http://www.microsoft.com/technet/support/kb.asp?ID=Q300972</a>
</DL>
</P>

<H2>References</H2>
<ol>
<A NAME=ref1></a>
<li><i>VU#952336: Microsoft Index Server/Indexing Service used by IIS 4.0/5.0 contains unchecked buffer used when encoding double-byte characters</i> CERT/CC, 06/19/2001, <a href="https://www.kb.cert.org/vuls/id/952336">https://www.kb.cert.org/vuls/id/952336</a></li> 
<a name=ref2></a>
<li>Additional advice on securing IIS web servers is available from<BR>
<dl><dd>
<A HREF="http://www.microsoft.com/technet/security/iis5chk.asp">http://www.microsoft.com/technet/security/iis5chk.asp</a>
<BR>
<A HREF="http://www.microsoft.com/technet/security/tools.asp">http://www.microsoft.com/technet/security/tools.asp</a>
</dl>
</ol>

Feedback concerning this document may be directed to <A HREF="mailto:cert@cert.org?subject=CA-2001-13%20Feedback%20VU%23952336">Jeffrey S. Havrilla</A>.

<P>

<!--#include virtual="/include/footer_nocopyright.html" -->

<P>Copyright 2001 Carnegie Mellon University.</P>

<P>Revision History
<PRE>
Jun 19, 2001: Initial Release
Jun 21, 2001: Removed statement about patch supersession
Jul 17, 2001: Updated Feedback link
Jul 30, 2001: Added link to Polish translation 
Aug 16, 2001: Added link to Microsoft Security Bulletin MS01-044
Jan 17, 2002: Updated Feedback link
</PRE>