Published:
16 October 2000
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-----BEGIN PGP SIGNED MESSAGE----- =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2000.290 -- Microsoft Security Bulletin (MS00-076) Patch Available for "Cached Web Credentials" Vulnerability 17 October 2000 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Internet Explorer 4.x Internet Explorer 5.x prior to version 5.5 Vendor: Microsoft Impact: Access Confidential Data Access Required: Local - --------------------------BEGIN INCLUDED TEXT-------------------- - -----BEGIN PGP SIGNED MESSAGE----- Microsoft Security Bulletin (MS00-076) - - -------------------------------------- Patch Available for "Cached Web Credentials" Vulnerability Originally posted: October 12, 2000 Summary ======= Microsoft has released a patch that eliminates a security vulnerability in Microsoft(r) Internet Explorer. Under a daunting set of conditions, the vulnerability could enable a malicious user to obtain another user's userid and password to a web site. Frequently asked questions regarding this vulnerability and the patch can be found at http://www.microsoft.com/technet/security/bulletin/fq00-076.asp Issue ===== When a user authenticates to a secured web page via Basic Authentication, IE caches the userid and password that were used, in order to minimize the number of times the user must authenticate to the same site. By design, IE should only send the cached credentials to secured pages on the site. However, it will actually send them to non-secure pages on the site as well. If a malicious user had complete control of another user's network communications, he could wait until another user logged onto a secured site, then spoof a request for a non-secured page in order to collect the credentials. The vulnerability does not provide a means by which the malicious user could force the other user to log onto a secure page of his choice, and could only be used to reveal credentials that had been cached during the current IE session. Affected Software Versions ========================== - Microsoft Internet Explorer 4.x - Microsoft Internet Explorer 5.x prior to version 5.5 Note: Internet Explorer 5.5 is not affected by this vulnerability. Customers using IE 5.5 do not need to take any action. Patch Availability ================== - http://www.microsoft.com/windows/ie/download/critical/q273868.htm Note: The patch requires IE 5.01 SP1 to install. Customers who install this patch on other versions may receive a message reading "This update does not need to be installed on this system". This message is incorrect. More information is available in KB article Q273868. Note: As discussed in Affected Software Versions, this vulnerability does not affect IE 5.5. Note: Per the normal security support policy for IE, security patches for Internet Explorer version 4.x are no longer being produced. Microsoft recommends that IE 4.x customers who are concerned about this issue consider upgrading to either IE 5.01 SP1 or IE 5.5. Note: The fix for this issue will be included in IE 5.01 SP2. 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 MS00-076, http://www.microsoft.com/technet/security/bulletin/fq00-076.asp - Microsoft Knowledge Base article Q273868 discusses this issue and will be available soon. - 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) for reporting this issue to us and working with us to protect customers. Revisions ========= - October 12, 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 12, 2000 (c) 2000 Microsoft Corporation. All rights reserved. Terms of use. - -----BEGIN PGP SIGNATURE----- Version: PGP Personal Privacy 6.5.3 iQEVAwUBOeaCz40ZSRQxA/UrAQGTjAf/Z/IALRk83Y3SZ3WqUHPzSjzDC/oxwfIP +eu00zpoWyzaWdUBb2J13O5nFz29L6UI3TQqmr8sbzcNdsKOziJz9jRIC1SYighN f69XF8kT6KK3qFobTYzFbGIUOoBY/PHVTqxddxJF80rgA59O/9yyE1u1bE3nYJcU CHGQIK7evTbBc7XQAK/kFn+q8LAo841E95almhmK2wihIDHHokk2bKxTr6xlXMzk yOEpHn/4V6HAi+g6Q6e3592XN+6YrPJ7iMUhbDrSTqWHR1lVQYCAHvMsga8JiJM1 ej4H13GzEm0nma5fM0f50QPyGAqeMInVEomrRqjEg39ZRg6R36d2pQ== =WAbA - -----END PGP SIGNATURE----- - --------------------------END INCLUDED TEXT-------------------- This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. 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Internet Email: auscert@auscert.org.au Facsimile: (07) 3365 7031 Telephone: (07) 3365 4417 (International: +61 7 3365 4417) AusCERT personnel answer during Queensland business hours which are GMT+10:00 (AEST). On call after hours for emergencies. -----BEGIN PGP SIGNATURE----- Version: 2.6.3i Charset: noconv Comment: ftp://ftp.auscert.org.au/pub/auscert/AUSCERT_PGP.key iQCVAwUBOlSNAih9+71yA2DNAQG58wP+PxD19ENAU5wXEJQv86W3AZIeMEveXlTj 6bZ3HZ0i/EuDiDbXzUa6k2TtlKuKvBB7tBnuue7PeewVgnMlbuORLAWLTGg149IY tp0iAa8JI6B6dOgTM/ygqaalrjWb8wcGqiGedMDJ1Vq83CJjnDIN9tDghEDEcDZm 3mRP6XwPP4M= =c2Hr -----END PGP SIGNATURE-----