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Microsoft Security Bulletin (MS99-017)
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Patch Available for "RAS and RRAS Password" Vulnerability
Originally Posted: May 27, 1999
Summary
=======
Microsoft has released a patch that eliminates a vulnerability in the
Microsoft (r) Windows NT (r) Remote Access Service (RAS) and Routing and
Remote Access Service (RRAS) clients, in which a user's password is cached
even if the user de-selects the "Save password" option.
Issue
=====
When the client software for Microsoft RAS or RRAS is used to dial into a
server, a dialogue requests the user's userid and password for the server.
On the same dialogue is a checkbox whose caption reads "Save password" and
which is intended to provide the user with the option to cache their
security credentials if desired. However, the implemented client
functionality actually caches the user's credentials regardless of whether
the checkbox is selected or de-selected.
Cached security credentials, which include the password, are stored in the
registry and protected by ACLs whose default values authorize only local
administrators and the user to access them. Windows NT 4.0 Service Pack 4
also provides the ability to strongly encrypts the password data stored in
the registry using the SYSKEY feature.
While there are no reports of customers being adversely affected by this
vulnerability, Microsoft is proactively releasing a patch that restores
correct functionality to the password caching function. The patch should be
applied to all machines that are used as RAS or RRAS clients. It is
important to note that RRAS servers also can be used as RRAS clients, and
any machines used in such a capacity should have the patch applied as well.
Affected Software Versions
==========================
- Microsoft Windows NT Workstation 4.0
- Microsoft Windows NT Server 4.0
- Microsoft Windows NT Server 4.0, Enterprise Edition
What Microsoft is Doing
=======================
Microsoft has released patches that fix the problem identified. The patches
are available for download from the sites listed below in What Customers
Should Do.
Microsoft also has sent this security bulletin to customers
subscribing to the Microsoft Product Security Notification Service.
See http://www.microsoft.com/security/services/bulletin.asp for
more information about this free customer service.
Microsoft has published the following Knowledge Base (KB) article on this
issue:
- Microsoft Knowledge Base (KB) article Q230681,
RAS Credentials Saved when "Save Password" Option Unchecked,
http://support.microsoft.com/support/kb/articles/q230/6/81.asp
- Microsoft Knowledge Base (KB) article Q233303,
RRAS Credentials Saved when "Save Password" Option Unchecked,
http://support.microsoft.com/support/kb/articles/q233/3/03.asp
(Note: It might take 24 hours from the original posting of this bulletin for
the KB article to be visible in the Web-based Knowledge Base.)
What Customers Should Do
========================
Microsoft highly recommends that customers evaluate the degree of risk that
this vulnerability poses to their systems and determine whether to download
and install the patch. The patch can be found at:
- RAS:
ftp://ftp.microsoft.com/bussys/winnt/winnt-public
/fixes/usa/nt40/Hotfixes-PostSP5/RASPassword-fix/
- RRAS:
ftp://ftp.microsoft.com/bussys/winnt/winnt-public
/fixes/usa/nt40/Hotfixes-PostSP5/RRASPassword-fix/
(Note: The URLs above have been wrapped for readability)
More Information
================
Please see the following references for more information related to this
issue.
- Microsoft Security Bulletin MS99-017,
Patch Available for "RAS and RRAS Password Caching"
Vulnerability, (The Web-posted version of this bulletin),
http://www.microsoft.com/security/bulletins/ms99-017.asp.
- Microsoft Knowledge Base (KB) article Q230681,
RAS Credentials Saved when "Save Password" Option Unchecked,
http://support.microsoft.com/support/kb/articles/q230/6/81.asp.
- Microsoft Knowledge Base (KB) article Q233303,
RRAS Credentials Saved when "Save Password" Option Unchecked,
http://support.microsoft.com/support/kb/articles/q233/3/03.asp
Obtaining Support on this Issue
===============================
If you require technical assistance with this issue, please
contact Microsoft Technical Support. For information on
contacting Microsoft Technical Support, please see
http://support.microsoft.com/support/contact/default.asp.
Revisions
=========
- May 27, 1999: Bulletin Created.
For additional security-related information about Microsoft products, please
visit http://www.microsoft.com/security
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(c) 1999 Microsoft Corporation. All rights reserved. Terms of Use.
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