-----BEGIN PGP SIGNED MESSAGE----- __________________________________________________________ The U.S. Department of Energy Computer Incident Advisory Capability ___ __ __ _ ___ / | /_\ / \___ __|__ / \ \___ __________________________________________________________ INFORMATION BULLETIN Microsoft "Malformed HTTP Request Header" Vulnerability August 12, 1999 17:00 GMT Number J-058 ______________________________________________________________________________ PROBLEM: Microsoft has identified a vulnerability that could cause a denial of service threat in web server products. PLATFORM: Microsoft(r) Internet Information Server 4.0 Microsoft Site Server 3.0 Microsoft Site Server 3.0, Commerce Edition Microsoft Commerce Internet Server 2.0 and 2.5 DAMAGE: The vulnerability could allow an attacker to submit requests containing specially-malformed headers which could consume all memory causing a denial of service. SOLUTION: Until the corrected version of the patch is released, restart the affected servers with a clean log file. ______________________________________________________________________________ VULNERABILITY Risk is medium. The HTTP request headers need to be specially ASSESSMENT: crafted to exploit this denial of service attack. ______________________________________________________________________________ This update was released by Microsoft on August 11, 1999 after they had released their Security Bulletin MS99-029. The original bulletin follows. ******************************** Since releasing Microsoft Security Bulletin MS99-029 earlier today, we have discovered a regression error in the patch that it discussed. The error has no effect on the bulletin -- all of the information in it is still valid -- but we have retracted the patch temporarily. We are working to remove the error, and will re-release the patch as soon as possible. We apologize for any inconvenience that this may cause. Information on the error and what customers should do is available at http://www.microsoft.com/security/bulletins/ms99-029regression.asp. However, the main points are: - The error does not invalidate the security bulletin. The vulnerability is bona fide, and we will re-release the patch as soon as possible. - The error could cause an IIS server to hang when the length of the IIS log file is an exact multiple of 64KB. - Affected servers can be put back in service by restarting IIS with a clean log file. - We recommend that customers who have not installed the patch delay doing so until the corrected version is available. We recommend that customers who have installed the patch do not attempt to "back out" the patch, but instead monitor their servers and stay alert to the presence of the error. - We are developing a corrected version of the patch and will re-release it as soon as possible When the corrected patch is available, we will provide information via http://www.microsoft.com/security and through the Microsoft Product Security Notification Service. Regards, The Microsoft Product Security Team [ Start Microsoft Bulletin ] ******************************** Microsoft Security Bulletin (MS99-029) - -------------------------------------- Patch Available for "Malformed HTTP Request Header" Vulnerability Originally Posted: August 11, 1999 Summary ======= Microsoft has released a patch that eliminates a vulnerability in web server products that use Microsoft(r) Internet Information Server 4.0 as their web engine. The vulnerability could be used to mount denial of service attacks against the web server. Frequently asked questions regarding this vulnerability can be found at http://www.microsoft.com/security/bulletins/MS99-029faq.asp Issue ===== If multiple HTTP requests containing specially-malformed headers are sent to an affected server, IIS may consume all memory on the server. If this happens, IIS would be unable to service requests until either the clients that issued the requests were closed, or the IIS service were stopped and restarted. Once either of these actions have occurred, normal service would be restored. Affected Software Versions ========================== - Microsoft Internet Information Server 4.0 - Microsoft Site Server 3.0 - Microsoft Site Server 3.0, Commerce Edition - Microsoft Commerce Internet Server 2.0 and 2.5 Patch Availability ================== - X86 version: ftp://ftp.microsoft.com/bussys/iis/iis-public/fixes /usa/security/hdbrk-fix/x86 - Alpha version: ftp://ftp.microsoft.com/bussys/iis/iis-public/fixes /usa/security/hdbrk-fix/alpha NOTE: Line breaks have been inserted in the above URLs for readability. More Information ================ Please see the following references for more information related to this issue. - Microsoft Security Bulletin MS99-029: Frequently Asked Questions, http://www.microsoft.com/security/bulletins/MS99-029faq.asp. - Microsoft Knowledge Base (KB) article Q238349, Specially-Malformed Header in HTTP Request Creates Denial of Service, http://support.microsoft.com/support/kb/articles/q238/3/49.asp. (Note: It may take 24 hours from the original posting of this bulletin for the KB article to be visible.) - Microsoft Security Advisor web site, http://www.microsoft.com/security/default.asp. Obtaining Support on this Issue =============================== This is a fully supported patch. Information on contacting Microsoft Technical Support is available at http://support.microsoft.com/support/contact/default.asp. Acknowledgments =============== Microsoft acknowledges Nobuo Miwa of the LAC SNS team for bringing this issue to our attention and working with us to alert customers about it. Revisions ========= - August 11, 1999: Bulletin Created. - --------------------------------------------------------------------------- THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. (c) 1999 Microsoft Corporation. All rights reserved. ******************************************************************* You have received this e-mail bulletin as a result of your registration to the Microsoft Product Security Notification Service. You may unsubscribe from this e-mail notification service at any time by sending an e-mail to MICROSOFT_SECURITY-SIGNOFF-REQUEST@ANNOUNCE.MICROSOFT.COM The subject line and message body are not used in processing the request, and can be anything you like. For more information on the Microsoft Security Notification Service please visit http://www.microsoft.com/security/services/bulletin.asp. For security-related information about Microsoft products, please visit the Microsoft Security Advisor web site at http://www.microsoft.com/security. [ End Microsoft Bulletin ] ______________________________________________________________________________ CIAC wishes to acknowledge Microsoft for the information contained in this bulletin. ______________________________________________________________________________ CIAC, the Computer Incident Advisory Capability, is the computer security incident response team for the U.S. Department of Energy (DOE) and the emergency backup response team for the National Institutes of Health (NIH). CIAC is located at the Lawrence Livermore National Laboratory in Livermore, California. CIAC is also a founding member of FIRST, the Forum of Incident Response and Security Teams, a global organization established to foster cooperation and coordination among computer security teams worldwide. CIAC services are available to DOE, DOE contractors, and the NIH. CIAC can be contacted at: Voice: +1 925-422-8193 FAX: +1 925-423-8002 STU-III: +1 925-423-2604 E-mail: ciac@llnl.gov For emergencies and off-hour assistance, DOE, DOE contractor sites, and the NIH may contact CIAC 24-hours a day. During off hours (5PM - 8AM PST), use one of the following methods to contact CIAC: 1. Call the CIAC voice number 925-422-8193 and leave a message, or 2. Call 888-449-8369 to send a Sky Page to the CIAC duty person or 3. Send e-mail to 4498369@skytel.com, or 4. Call 800-201-9288 for the CIAC Project Leader. Previous CIAC notices, anti-virus software, and other information are available from the CIAC Computer Security Archive. World Wide Web: http://www.ciac.org/ (or http://ciac.llnl.gov -- they're the same machine) Anonymous FTP: ftp.ciac.org (or ciac.llnl.gov -- they're the same machine) Modem access: +1 (925) 423-4753 (28.8K baud) +1 (925) 423-3331 (28.8K baud) CIAC has several self-subscribing mailing lists for electronic publications: 1. CIAC-BULLETIN for Advisories, highest priority - time critical information and Bulletins, important computer security information; 2. SPI-ANNOUNCE for official news about Security Profile Inspector (SPI) software updates, new features, distribution and availability; 3. SPI-NOTES, for discussion of problems and solutions regarding the use of SPI products. Our mailing lists are managed by a public domain software package called Majordomo, which ignores E-mail header subject lines. To subscribe (add yourself) to one of our mailing lists, send the following request as the E-mail message body, substituting ciac-bulletin, spi-announce OR spi-notes for list-name: E-mail to ciac-listproc@llnl.gov or majordomo@rumpole.llnl.gov: subscribe list-name e.g., subscribe ciac-bulletin You will receive an acknowledgment email immediately with a confirmation that you will need to mail back to the addresses above, as per the instructions in the email. This is a partial protection to make sure you are really the one who asked to be signed up for the list in question. If you include the word 'help' in the body of an email to the above address, it will also send back an information file on how to subscribe/unsubscribe, get past issues of CIAC bulletins via email, etc. PLEASE NOTE: Many users outside of the DOE, ESnet, and NIH computing communities receive CIAC bulletins. If you are not part of these communities, please contact your agency's response team to report incidents. Your agency's team will coordinate with CIAC. The Forum of Incident Response and Security Teams (FIRST) is a world-wide organization. A list of FIRST member organizations and their constituencies can be obtained via WWW at http://www.first.org/. This document was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor the University of California nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation or favoring by the United States Government or the University of California. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or the University of California, and shall not be used for advertising or product endorsement purposes. LAST 10 CIAC BULLETINS ISSUED (Previous bulletins available from CIAC) J-048: Malformed HTR Request Vulnerability J-049: Windows NT, Two Denial-of-Service Vulnerabilities J-050: HP-UX Visualize Conference Vulnerability J-051: Calendar Manager Service Buffer Overflow Vulnerability J-052: SGI arrayd default security configuration J-053: HP Current Directory Vulnerability J-054: Unauthorized Access to IIS Servers through ODBC Data Access with RDS J-055: IBM AIX Vulnerability in ptrace() system call J-056: Microsoft "Encapsulated SMTP Address" Vulnerability J-057: Windows NT(r) Terminal Servers DOS Vulnerability -----BEGIN PGP SIGNATURE----- Version: 4.0 Business Edition iQCVAwUBN7MG6rnzJzdsy3QZAQE8UwQAy1+6+9Dvu7JT3OnPaU0W/QM9LW3tyU1K ewmUBHFCdaH2jMsHIELz14/Y0d4aKKgTxfGOG9wmn8qZ4CctOn4r1EMSRo8zBSMZ erEnLpSHHZWNIcLyENzvS1FfFfn6vWMK9xFh7m+qKiIiWHTfwvnDRlS4TU14zQPs 10QLSPyfp1s= =gq14 -----END PGP SIGNATURE-----