AUSCERT External Security Bulletin Redistribution
                   ESB-1999.081 -- CERT Advisory CA-99-07
                New Information regarding IIS Buffer Overflow
                                21 June 1999


The CERT Coordination Centre has released the following advisory containing
new information regarding the IIS buffer overflow vulnerability. New
information released by Microsoft has indicated that the vulnerability
affects several libraries, including libraries that handle .HTR, .STM,
and .IDC files. This vulnerability may allow remote intruders to crash
IIS and execute arbitrary code on the server with the privileges of IIS.

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CERT Advisory CA-99-07 IIS Buffer Overflow

   Revised: June 18, 1999
   Originally released: June 16, 1999
   Source: CERT/CC

Note: This re-distribution of CA-99-07 contains new information
regarding variations of the IIS vulnerability that was widely reported
this week. In particular, we encourage sites to obtain and install the
patch that is available from Microsoft which addresses all of the
variations of this vulnerability.
Systems Affected

     * Machines running Microsoft Internet Information Server 4.0
I. Description

   Buffer overflow vulnerabilities affecting Microsoft Internet
   Information Server 4.0 have been discovered in several libraries,
   including libraries that handle .HTR, .STM, and .IDC files.
   A tool to exploit at least one of the vulnerabilities has been
   publicly released.
II. Impact

   These vulnerabilities allow remote intruders to execute arbitrary code
   with the privileges of the IIS server. Additionally, intruders can use
   this vulnerability to crash vulnerable IIS processes.
III. Solution

   Microsoft has released and updated Microsoft Security Bulletin
   MS99-019, which points to a patch for these vulnerabilities. We
   encourage you to read this bulletin, available from
   We will update this advisory as more information becomes available.
   Please check the CERT/CC Web site for the most current revision.
   Our thanks to Jason Garms and Scott Culp of Microsoft for providing
   information contained in this advisory.
   This document is available from:
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
   CERT personnel answer the hotline 08:00-20:00 EST(GMT-5) / EDT(GMT-4)
   Monday through Friday; they are on call for emergencies during other
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Getting security information

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   Copyright 1999 Carnegie Mellon University.
   Conditions for use, disclaimers, and sponsorship information can be
   found in http://www.cert.org/legal_stuff.html.
   * "CERT" and "CERT Coordination Center" are registered in the U.S.
   Patent and Trademark Office
   Any material furnished by Carnegie Mellon University and the Software
   Engineering Institute is furnished on an "as is" basis. Carnegie
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   Revision History

June 16, 1999:  Initial release
June 18, 1999:  Added information about .STM and .IDC files.

Version: 2.6.2


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