April 11, 2002 Security Advisory If your website resides on an IIS server, please read on. If your website resides on an IIS server hosted by an ISP, I urge you to forward this email to your ISP and request that the patches and procedures outlined below be immediately implemented. The Computer Emergency Response Team just released this security advisory: CERT Advisory CA-2002-09 Multiple Vulnerabilities in Microsoft IIS Original release date: April 11, 2002 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 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. 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 subscribe to the CERT mailing list for advisories and bulletins, send email to majordomo@cert.org. Please include in the body of your message subscribe cert-advisory * "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. _________________________________________________________________ Conditions for use, disclaimers, and sponsorship information Copyright 2002 Carnegie Mellon University. Revision History April 11, 2002: Initial release