From secnotif@MICROSOFT.COM Thu Sep 30 21:08:29 1999 From: Microsoft Product Security Resent-From: mea culpa To: MICROSOFT_SECURITY@ANNOUNCE.MICROSOFT.COM Resent-To: jericho@attrition.org Date: Thu, 30 Sep 1999 18:48:31 -0700 Subject: Microsoft Security Bulletin (MS99-039) 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. ******************************** Microsoft Security Bulletin (MS99-039) -------------------------------------- Update: Patch Available for "Domain Resolution" and "FTP Download" Vulnerabilities Originally Posted: September 23, 1999 Revised: September 30, 1999 Summary ======= This is a re-release of a security bulletin issued on September 23, 1999. The purpose of the re-release is to discuss an additional product, Microsoft(r) Commercial Internet System, that is affected by this vulnerability. The information regarding IIS has not changed, and customers who previously applied this patch to their IIS systems do not need to take any action. Microsoft has released a patch that eliminates two security vulnerabilities in Microsoft Internet Information Server (IIS) 4.0 and Microsoft Commercial Internet System (MCIS) 2.5. The vulnerabilities allow security restrictions in IIS and MCIS to be bypassed under certain conditions, as discussed below. Frequently asked questions regarding this vulnerability can be found at http://www.microsoft.com/security/bulletins/ms99-039faq.asp. Issue ===== There are two vulnerabilities at issue here: - IIS 4.0 provides the ability to restrict access to a web site based on the user's domain. However, if IIS cannot resolve a user's IP address to a domain, it will grant the user's first request for a session. It will correctly deny them thereafter. This vulnerability affects IIS 4.0 only; it does not any other Microsoft product, including MCIS. - A user who accesses an FTP site via a browser will be able to download files even if they are marked No Access. This vulnerability is due to a regression error that was introduced in hotfixes released after Windows NT 4.0 Service Pack 5; it does not exist in SP5 or in previous versions. This vulnerability affects both IIS 4.0 and MCIS 2.5, but no other Microsoft products. Neither vulnerability provides a means to usurp control of the server. A patch is available that eliminates both vulnerabilities. Affected Software Versions ========================== - Microsoft Internet Information Server 4.0 - Microsoft Commercial Internet System 2.5 Patch Availability ================== - IIS 4.0: ftp://ftp.microsoft.com/bussys/iis/iis-public/fixes/ usa/IIS40/hotfixes-postSP6/security/IPRFTP-fix/ - MCIS 2.5: ftp://ftp.microsoft.com/bussys/mcis/mcis-public/fixes/ usa/mcis25/security/ftpsvc-fix/ NOTE: Line breaks have been inserted into the above URLs for readability. More Information ================ Please see the following references for more information related to this issue. - Microsoft Security Bulletin MS99-039: Frequently Asked Questions, http://www.microsoft.com/security/bulletins/ms99-039faq.asp. - Microsoft Knowledge Base (KB) article Q241805, Combined FTP and Domain Restriction Security Patch for IIS 4.0, http://support.microsoft.com/support/kb/articles/q241/8/05.asp. - Microsoft Knowledge Base (KB) article Q241562, Denying Access With Domain Name Restriction Still Allows Unresolved Clients, http://support.microsoft.com/support/kb/articles/q241/5/62.asp. - Microsoft Knowledge Base (KB) article Q241407, Files can be downloaded from an FTP Server when the file permissions are explicitly No Access, http://support.microsoft.com/support/kb/articles/q241/4/07.asp. - Microsoft Knowledge Base (KB) article Q242559, FTP Allows read on a file with NTFS permissions of No Access, http://support.microsoft.com/support/kb/articles/q242/5/59.asp. - Microsoft Security Advisor web site, http://www.microsoft.com/security/default.asp. (Note: It may take 24 hours from the original posting of this bulletin for the KB articles to be visible.) 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 Rich Harrison of Halliburton Company for discovering the "Domain Resolution" vulnerability and reporting it to us. Microsoft acknowledges Roberto Franceschetti for discovering the FTP Access vulnerability and bringing it to our attention. Revisions ========= - September 23, 1999: Bulletin Created. - September 30, 1999: Bulletin modified to include information regarding MCIS association with this vulnerability. ---------------------------------------------------------------------- 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. Terms of Use ******************************************************************* You have received this e-mail bulletin as a result of your registration to the Microsoft Product Security Notification Service. 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