From secnotif@MICROSOFT.COM Sun May 14 13:43:07 2000 From: Microsoft Product Security Resent-From: mea culpa To: MICROSOFT_SECURITY@ANNOUNCE.MICROSOFT.COM Resent-To: jericho@attrition.org Date: Thu, 11 May 2000 13:33:07 -0700 Subject: Microsoft Security Bulletin (MS00-030) The following is a Security Bulletin from the Microsoft Product Security Notification Service. Please do not reply to this message, as it was sent from an unattended mailbox. ******************************** -----BEGIN PGP SIGNED MESSAGE----- Microsoft Security Bulletin (MS00-030) - -------------------------------------- Patch Available for "Malformed Extension Data in URL" Vulnerability Originally Posted: May 11, 2000 Summary ======= Microsoft has released a patch that eliminates a security vulnerability in Microsoft(r) Internet Information Server. The vulnerability could be used to slow the performance of an affected server, or temporarily stop it altogether. Frequently asked questions regarding this vulnerability and the patch can be found at http://www.microsoft.com/technet/security/bulletin/fq00-030.asp Issue ===== In compliance with RFC 2396, the algorithm in IIS that processes URLs has flexibility built in to allow it to process any arbitrary sequence of file extensions or subresource identifiers (referred to in the RFC as path_segments). By providing an URL that contains specially-malformed file extension information, a malicious user could misuse this flexibility in order to arbitrarily increase the work factor associated with parsing the URL. This could consume much or all of the CPU availability on the server and prevent useful work from being done. The vulnerability does not provide any capability to cause the server to fail, or to add, change or delete data on it. Likewise, it provides no capability to usurp administrative control of the web server. The slowdown would only last until the URL had been processed, at which point service would return to normal. Affected Software Versions ========================== - Microsoft Internet Information Server 4.0 - Microsoft Internet Information Server 5.0 Patch Availability ================== - Internet Information Server 4.0: http://www.microsoft.com/Downloads/Release.asp?ReleaseID=20906 - Internet Information Server 5.0: http://www.microsoft.com/Downloads/Release.asp?ReleaseID=20904 Note: Additional security patches are available at the Microsoft Download Center More Information ================ Please see the following references for more information related to this issue. - Frequently Asked Questions: Microsoft Security Bulletin MS00-030, http://www.microsoft.com/technet/security/bulletin/fq00-030.asp - Microsoft Knowledge Base article Q260205 discusses this issue and will be available soon. - RFC 2396, Uniform Resource Identifiers (URI): Generic Syntax, http://www.ietf.org/rfc/rfc2396.txt. - Microsoft TechNet Security web site, http://www.microsoft.com/technet/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 thanks Underground Security Systems Research (http://www.ussrback.com) for reporting this vulnerability to us and working with us to protect customers. Revisions ========= - May 11, 2000: 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. Last updated May 11, 2000 (c) 2000 Microsoft Corporation. All rights reserved. Terms of use. -----BEGIN PGP SIGNATURE----- Version: PGP 6.0.2 iQEVAwUBORsZJI0ZSRQxA/UrAQGNXwf6AoNSLl3XaKonXLij7Y62diSAM19gZnf0 p8Otv1yLL2OYKI9RHuLzQWnAADNUiR04qzZXxdyQOCuVk5L8+ss5d1IxUuZYfwud S+yXXoPk0VYTZBoBpvRYtCc5t9jkWWqh83RtVdWwek0EAcfWfXiQZ00W+Oh9Tqv2 F44NZCJ5xmpvzodwZWihumPLOFDD3uNXxEps5RwG8r/4HELbdfJY/9D2BTWGZL1v vTYOeoU2+qIR3WC3dw/Peh8mi0mPPrmvpUPGi6JSBQ1zb+tvXE5pawxq75QW6nM3 5haGVhnx46zsiaPHxU/hVadzSYAihD5Uq5rqwRhK6Xz+/obyJZj2fw== =5Ikr -----END PGP SIGNATURE----- ******************************************************************* You have received this e-mail bulletin as a result of your registration to the Microsoft Product Security Notification Service. 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