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Microsoft Security Bulletin (MS00-080)
From: Microsoft Product Security <secnotif () MICROSOFT COM>
Date: Mon, 23 Oct 2000 20:07:00 -0700
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 (MS00-080) - -------------------------------------- Patch Available for "Session ID Cookie Marking" Vulnerability Originally posted: October 23, 2000 Summary ======= Microsoft has released a patch that eliminates a security vulnerability in Microsoft(r) Internet Information Server. The vulnerability could allow a malicious user to "hijack" another user's secure web session, under a very restricted set of circumstances. Frequently asked questions regarding this vulnerability and the patch can be found at http://www.microsoft.com/technet/security/bulletin/fq00-080.asp Issue ===== IIS supports the use of a Session ID cookie to track the current session identifier for a web session. However, .ASP in IIS does not support the creation of secure Session ID cookies as defined in RFC 2109. As a result, secure and non-secure pages on the same web site use the same Session ID. If a user initiated a session with a secure web page, a Session ID cookie would be generated and sent to the user, protected by SSL. But if the user subsequently visited a non-secure page on the same site, the same Session ID cookie would be exchanged, this time in plaintext. If a malicious user had complete control over the communications channel, he could read the plaintext Session ID cookie and use it to connect to the user's session with the secure page. At that point, he could take any action on the secure page that the user could take. The conditions under which this vulnerability could be exploited are rather daunting. The malicious user would need to have complete control over the other user's communications with the web site. Even then, the malicious user could not make the initial connection to the secure page - only the legitimate user could do that. The patch eliminates the vulnerability by adding support for secure Session ID cookies in .ASP pages. (Secure cookies already are supported for all other types of cookies, under all other technologies in IIS). Affected Software Versions ========================== - Microsoft Internet Information Server 4.0 - Microsoft Internet Information Services 5.0 Patch Availability ================== - IIS 4.0: http://www.microsoft.com/Downloads/Release.asp?ReleaseID=25233 - IIS 5.0: http://www.microsoft.com/Downloads/Release.asp?ReleaseID=25232 Note: The patch installs support for secure Session ID cookies, but does not enable it for reasons of application compatibility. As discussed in the Knowledge Base article, it can be enabled or disabled on a site-by-site basis. Note: - The IIS 4.0 version of this patch can be installed on Windows NT(r) 4.0 systems running Service Pack 6a, and will be included in Service Pack 7. - The IIS 5.0 version of this patch can be installed on Windows(r) 2000 systems with or without Service Pack 1, and will be included in Service Pack 2. 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 MS00-080, http://www.microsoft.com/technet/security/bulletin/fq00-080.asp - Microsoft Knowledge Base article Q274149 discusses this issue and will be available soon. - RFC 2109, HTTP State Management, http://www.ietf.org/rfc/rfc2109.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 Product Support Services is available at http://support.microsoft.com/support/contact/default.asp. Acknowledgments =============== Microsoft thanks ACROS Security (http://www.acros.si/) and Ron Sires and C. Conrad Cady of Healinx (http://www.healinx.com/) for reporting this issue to us and working with us to protect customers. Revisions ========= - October 23, 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 October 23, 2000 -----BEGIN PGP SIGNATURE----- Version: PGP Personal Privacy 6.5.3 iQEVAwUBOfT80o0ZSRQxA/UrAQHKGgf7BBNBM8b4gQwlbVBJAeRh8deRWqksPhCv QKzFVQI11yzGF2jB0hEScFM4GygBjGshigHRa18fO/Op+AKseiIK9xkTAlm/RpEd epRC4M4lj6YGqMQpJ4uk4ovyWWdL/ZxQcEzDqCGUvckniRUlPI4A6j+3F+igzdFC Apqdu3I7V46Dp0qMHGRZ65uSoepbXPepQ2igy1REyIAUuBndBZR+FfP/U/8QM/t3 aY6FObaQqMorTmKX0FqKxLXV5uyPIJeZGzkMtU/falik7yEpEXrpJqg/+GHAfkUY 0J0wH4m1qURenKj5GPUapVlm4FQJ0hUEcN6U3k0O3UsOpGj3tciSTg== =rzSg -----END PGP SIGNATURE----- ******************************************************************* 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. 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