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              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
   
   http://www.microsoft.com/security/bulletins/ms99-019.asp
          
   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:
   http://www.cert.org/advisories/CA-99-07-IIS-Buffer-Overflow.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 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
   hours, on U.S. holidays, and on weekends.
   
Using encryption

   We strongly urge you to encrypt sensitive information sent by email.
   Our public PGP key is available from http://www.cert.org/CERT_PGP.key.
   If you prefer to use DES, please call the CERT hotline for more
   information.
   
Getting security information

   CERT publications and other security information are available from
   our web site http://www.cert.org/.
   
   To be added to our mailing list for advisories and bulletins, send
   email to cert-advisory-request@cert.org and include SUBSCRIBE
   your-email-address in the subject of your message.
   
   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
   ______________________________________________________________________
   
   NO WARRANTY
   Any material furnished by Carnegie Mellon University and the Software
   Engineering Institute is furnished on an "as is" basis. Carnegie
   Mellon University makes no warranties of any kind, either expressed or
   implied as to any matter including, but not limited to, warranty of
   fitness for a particular purpose or merchantability, exclusivity or
   results obtained from use of the material. Carnegie Mellon University
   does not make any warranty of any kind with respect to freedom from
   patent, trademark, or copyright infringement.
   Revision History

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

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This security bulletin is provided as a service to AusCERT's members.  As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content.  The decision to use any or all of this information is
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NOTE: This is only the original release of the security bulletin.  It will
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Previous advisories and external security bulletins can be retrieved from:

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If you believe that your system has been compromised, contact AusCERT or
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Internet Email: auscert@auscert.org.au
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