Microsoft Security Bulletin MS99-017 - Important
Patch Available for "RAS and RRAS Password" Vulnerability
Published: May 27, 1999 | Updated: March 21, 2003
Patch Availability Information Updated: March 21, 2003
Originally Posted: May 27, 1999
Microsoft has released a patch that eliminates a vulnerability in the Microsoft® Windows NT® 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.
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 and encrypted in the registry and protected by ACLs whose default values authorize only local administrators and the owner of the credentials 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 RAS 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
Vulnerability Identifier: CVE-1999-0755
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 <a href="/technet/security/bulletin/notify.mspx"& The Microsoft Product Security Notification Service 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 230681, DUN Credentials Cached When Save Password Not Selected with RAS, http://support.microsoft.com/default.aspx?scid=kb;en-us;230681&sd=tech
Microsoft Knowledge Base (KB) article 233303, DUN Credentials Cached When Save Password Not Selected with RRAS, http://support.microsoft.com/default.aspx?scid=kb;en-us;233303&sd=tech
(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: http://www.microsoft.com/technet/security/patchavailability.mspx
- RRAS: http://www.microsoft.com/technet/security/patchavailability.mspx
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/technet/security/bulletin/ms99-017.mspx.
- Microsoft Knowledge Base (KB) article 230681, DUN Credentials Cached When Save Password Not Selected with RAS, http://support.microsoft.com/default.aspx?scid=kb;en-us;230681&sd=tech.
- Microsoft Knowledge Base (KB) article 233303, DUN Credentials Cached When Save Password Not Selected with RRAS, http://support.microsoft.com/default.aspx?scid=kb;en-us;233303&sd=tech
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/contactussupport/?ws=support.
- May 27, 1999: Bulletin Created.
- V2.0 (March 21, 2003): Introduced versioning and updated patch availability information
For additional security-related information about Microsoft products, please visit http://www.microsoft.com/technet/security
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