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CERT Advisory CA-2002-09 Multiple Vulnerabilities in Microsoft IIS

   Original release date: April 11, 2002
   Last revised: --
   Source: CERT/CC

   A complete revision history can be found at the end of this file.

Systems Affected

     * Microsoft IIS 4.0, 5.0, and 5.1

Overview

   A variety of vulnerabilities exist in various versions of Microsoft
   IIS. Some of these vulnerabilities may allow an intruder to execute
   arbitrary code on vulnerable systems.

I. Description

   There are a variety of vulnerabilities in Microsoft IIS. Many of these
   vulnerabilities are buffer overflows that could permit an intruder to
   execute arbitrary code on vulnerable systems.
   We strongly encourage all sites running IIS to read Microsoft's
   advisory on these and other vulnerabilities and take appropriate
   action as soon as practical. Microsoft's bulletin is available at

          http://www.microsoft.com/technet/security/bulletin/MS02-018.asp

   Additional information about these vulnerabilities is available at

          http://www.kb.cert.org/vuls

   VU#363715 CAN-2002-0071 Microsoft Internet Information Server (IIS)
             vulnerable to heap overflow during processing of crafted
             ".htr" request by "ISM.DLL" ISAPI filter

   VU#883091 CAN-2002-0074 Microsoft Internet Information Server (IIS)
             contains cross-site scripting vulnerability in IIS Help
             Files search facility

   VU#886699 CAN-2002-0148 Microsoft Internet Information Server (IIS)
             contains cross-site scripting vulnerability in HTTP error
             page results

   VU#520707 CAN-2002-0075 Microsoft Internet Information Server (IIS)
             contains cross-site scripting vulnerability in redirect
             response messages

   VU#412203 CAN-2002-0073 Microsoft Internet Information Server (IIS)
             vulnerable to DoS via malformed FTP connection status
             request

   VU#454091 CAN-2002-0150 Microsoft Internet Information Server (IIS)
             vulnerable to buffer overflow via inaccurate checking of
             delimiters in HTTP header fields

   VU#721963 CAN-2002-0149 Microsoft Internet Information Server (IIS)
             buffer overflow in server-side includes (SSI) containing
             long invalid file name

   VU#521059 CAN-2002-0072 Microsoft Internet Information Server (IIS)
             vulnerable to DoS when URL request exceeds maximum
             allowed length

   VU#610291 CAN-2002-0079 Microsoft Internet Information Server (IIS)
             buffer overflow in chunked encoding transfer mechanism

   VU#669779 CAN-2002-0147 Microsoft Internet Information Server (IIS)
             buffer overflow in chunked encoding transfer mechanism

II. Impact

   For many of the vulnerabilities, an intruder could execute arbitrary
   code with privileges that vary according to which version of IIS is
   running. In general, IIS 4.0 permits an intruder to execute code with
   complete administrative privileges, while IIS 5.0 and 5.1 permit an
   intruder to execute code with the privileges of the IWAM_computername
   account.

III. Solution

   Microsoft Corporation has released Microsoft Security Bulletin
   MS02-018, which announces the availability of a cumulative patch to
   address a variety of problems. We strongly encourage you to read this
   bulletin and take the appropriate corrective measures. MS02-018 is
   available at

          http://www.microsoft.com/technet/security/bulletin/MS02-018.asp

   In addition to applying the patch, or until it can be applied, we
   recommend the following actions:

     * Use the IIS Lockdown tool and URLScan to eliminate or reduce the
       impact of some of these vulnerabilites; they may also eliminate or
       reduce other vulnerabilities that have not yet been discovered.
       The IIS Lockdown tool can also be used to disable ASP if it's not
       needed. More information about the IIS Lockdown tool and URLScan
       can be found at

          http://www.microsoft.com/technet/security/tools/locktool.asp
                
          http://www.microsoft.com/technet/security/URLScan.asp

     * As Microsoft has recommended for quite some time, disable the HTR
       ISAPI extension unless it is absolutely required.
     * Disable anonymous FTP unless it is required.
     * Don't give login credentials on IIS servers to untrusted users.
     _________________________________________________________________

   Our thanks to Microsoft Corporation for the information contained in
   their advisory. Additionally, our thanks go to the various individuals
   and organizations whom Microsoft identified as discovering the
   vulnerabilities, including eEye Digital Security
   (http://www.eeye.com), Serge Mister of Entrust, Inc.
   (http://www.entrust.com), Dave Aitel of @Stake
   (http://www.atstake.com), Peter Grundl of KPMG, Joe Smith
   (jsm1th@hotmail.com) and zenomorph (admin@cgisecurity.com) of
   http://www.cgisecurity.com, Keigo Yamazaki of the LAC SNS Team
   (http://www.lac.co.jp/security/), and Thor Larholm of Jubii A/S.
     _________________________________________________________________

   Author: Shawn V. Hernan
   ______________________________________________________________________

   This document is available from:
   http://www.cert.org/advisories/CA-2002-09.html
   ______________________________________________________________________

CERT/CC Contact Information

   Email: cert@cert.org
          Phone: +1 412-268-7090 (24-hour hotline)
          Fax: +1 412-268-6989
          Postal address:
          CERT Coordination Center
          Software Engineering Institute
          Carnegie Mellon University
          Pittsburgh PA 15213-3890
          U.S.A.

   CERT/CC personnel answer the hotline 08:00-17:00 EST(GMT-5) /
   EDT(GMT-4) Monday through Friday; they are on call for emergencies
   during other hours, on U.S. holidays, and on weekends.

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Getting security information

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   ______________________________________________________________________

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   Any material furnished by Carnegie Mellon University and the Software
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     _________________________________________________________________

   Conditions for use, disclaimers, and sponsorship information

   Copyright 2002 Carnegie Mellon University.

   Revision History
April 11, 2002: Initial release

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