Microsoft Security Bulletin (MS99-052)

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Patch Available for "Legacy Credential Caching" Vulnerability

Originally Posted: November 29, 1999



Summary

=======

Microsoft has released a patch that eliminates a security vulnerability in

Microsoft(r)  Windows(r) 95 and 98 caused by a legacy mechanism for caching

network security credentials. The  vulnerability could allow a user's

plaintext network password to be retrieved from the cache.



Frequently asked questions regarding this vulnerability can be found at

http://www.microsoft.com/security/bulletins/MS99-052faq.asp.



Issue

=====

Windows for Workgroups(r) provided a RAM-based caching mechanism that cached

the user's plaintext  network credentials for use by real-mode command-line

networking utilities. Part of this  mechanism was carried forward into the

Windows 95 and 98 designs, even though it is not used by  either. A

malicious user could query this mechanism to obtain the network credentials

of the last  person to use the machine for network access, as long as they

had physical access to the machine  and it had not been rebooted since the

last networking session.



Affected Software Versions

==========================

 - Microsoft Windows 95

 - Microsoft Windows 98



Patch Availability

==================

 - Windows 95:

   http://www.microsoft.com/windows95/downloads/

   contents/WUCritical/password/default.asp

 - Windows 98:

   http://www.microsoft.com/windows98/downloads/

   contents/WUCritical/password/default.asp



NOTE: Line breaks have been inserted into the above URLs for readability.



NOTE: Windows 98 Second Edition is not affected by this vulnerability.



More Information

================

Please see the following references for more information related to this

issue.

 - Microsoft Security Bulletin MS99-052: Frequently Asked Questions,

   http://www.microsoft.com/security/bulletins/MS99-052faq.asp.

 - Microsoft Knowledge Base (KB) article Q168115,

   Windows Security Update Prevents Reading Domain Password,

   http://support.microsoft.com/support/kb/articles/q168/1/15.asp.

   (Note: It may take 24 hours from the original posting of this bulletin

   for this KB article to be visible.)

 - Microsoft Security Advisor web site,

   http://www.microsoft.com/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

=========

 - November 29, 1999: Bulletin Created.



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