CERT^® Advisory CA-1999-07 IIS Buffer Overflow

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

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.

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.

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/

* "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.

Copyright 1999 Carnegie Mellon University.

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