From secnotif@MICROSOFT.COM Fri Mar 31 03:58:39 2000 From: Microsoft Product Security Resent-From: mea culpa To: MICROSOFT_SECURITY@ANNOUNCE.MICROSOFT.COM Resent-To: jericho@attrition.org Date: Thu, 30 Mar 2000 10:43:49 -0800 Subject: Microsoft Security Bulletin (MS00-019) 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 (MS00-019) - -------------------------------------- Patch Available for "Virtualized UNC Share" Vulnerability Originally Posted: March 30, 2000 Summary - ------- Microsoft has released a patch that eliminates a security vulnerability in Microsoft(r) Internet Information Server and products based on it. Under certain fairly unusual conditions, the vulnerability could cause a web server to send the source code of .ASP and other files to a visiting user. Frequently asked questions regarding this vulnerability and the patch can be found at http://www.microsoft.com/technet/security/bulletin/fq00-019.asp Issue - ----- If a virtual directory on an IIS server is mapped to a UNC share, and a request for a file in the directory contains one of several particular characters at the end, the expected ISAPI extension processing may not occur. The result is that the source code of the file would be sent to the browser. There are significant restrictions that would increase the difficulty of exploiting this vulnerability: - By design, virtual directories hide the actual location of files. Under most circumstances, there would be no way for an attacker to determine which files on a server actually reside on a UNC share. - Many browsers will "correct" requests that contain the trailing characters at issue here, by either removing the characters or changing them. - If recommended security practices are followed, .ASP and other files that require server-side processing will not contain any sensitive information to compromise. Affected Software Versions ========================== - Microsoft Internet Information Server 4.0 and 5.0 - Microsoft Proxy Server 2.0 - Microsoft Site Server and Site Server, Commerce Edition 3.0 - Microsoft Commercial Internet System 2.0 and 2.5 Patch Availability ================== - Internet Information Server 4.0 Intel: http://www.microsoft.com/downloads/release.asp?ReleaseID=18900 Alpha: http://www.microsoft.com/downloads/release.asp?ReleaseID=18901 - Internet Information Server 5.0 http://www.microsoft.com/downloads/release.asp?ReleaseID=19982 NOTE: Proxy Server, Site Server, Site Server Commerce Edition and Microsoft Commercial Internet System run atop IIS. Customers using these products should apply the patch appropriate for the version of IIS they are running. 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 MS00-019, http://www.microsoft.com/technet/security/bulletin/fq00-019.asp. - Microsoft Knowledge Base (KB) article Q249599, Virtual Directory Mapped to UNC Returns Server-Side Script Code When URL Contains Additional Characters at the End of the Request, http://www.microsoft.com/technet/support/kb.asp?ID=249599. - 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. Revisions ========= - March 30, 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 March 30, 2000 (c) 2000 Microsoft Corporation. All rights reserved. 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