CERT^® Advisory CA-99-07 IIS Buffer Overflow

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

Systems Affected

Machines running Microsoft Internet Information Server 4.0.

I. Description

A buffer overflow vulnerability affecting Microsoft Internet Information Server 4.0 has been discovered in the ISM.DLL library. According to Microsoft, ISM.DLL is the "filter DLL that processes .HTR files. HTR files enable remote administration of user passwords."

A tool to exploit this vulnerability has been publicly released.

II. Impact

This vulnerability allows 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 Microsoft Security Bulletin MS99-019 describing a workaround to this problem. Additionally, Microsoft is working on a patch to fix this problem; information regarding this patch will be available in the Microsoft Security Bulletin. 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.

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.
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Revision History



June 16, 1999:  Initial release

CERT® Advisory CA-99-07 IIS Buffer Overflow