Windows 95 Update Prevents Sending Clear-Text Password Over NetLast reviewed: March 18, 1998Article ID: Q165403 |
The information in this article applies to:
SYMPTOMSUsing a program specifically designed for such a purpose, it may be possible to force a Windows 95-based computer running the Microsoft Client for Microsoft Networks to send a user's logon name and password across the network in a clear-text format, instead of the normal encrypted format. It may then be possible to intercept and read that password using such a program.
CAUSEWhen a Windows 95-based computer running the Microsoft Client for Microsoft Networks (which uses the SMB file-sharing protocol) connects to an SMB server, a negotiation takes place to determine which dialect of the SMB protocol will be used for communication. Microsoft Networking clients and servers generally support the ability to use older SMB dialects to support interoperability with older products. Some of these older dialects do not support sending passwords over the network in an encrypted form. When such a dialect is negotiated, passwords are sent over the network in clear-text form.
RESOLUTIONThis issue is resolved by the following updated files for Windows 95:
Vredir.vxd version 4.00.1114 (dated 6/2/97) and later Vnetsup.vxd version 4.00.1112 (dated 6/2/97) and laterTo install this update, follow these steps:
~ Vrdrupd.exe (size: 215728 bytes)For more information about downloading files from the Microsoft Software Library, please see the following article in the Microsoft Knowledge Base:
ARTICLE-ID: Q119591 TITLE : How to Obtain Microsoft Support Files from Online ServicesThe following files are installed by Vrdrupd.exe:
File name Version Date/Time Size Destination folder --------------------------------------------------------------------- Vredir.vxd 4.00.1114 6/2/97 11:14a 156,773 Windows\System Vnetsup.vxd 4.00.1112 6/2/97 11:12a 17,595 Windows\System MORE INFORMATIONWith this update installed, connecting to older SMB servers using the Client for Microsoft Networks is no longer possible, because these older servers do not support encryption of passwords sent over the network. The following SMB servers are known not to support password encryption over the network:
http://www.microsoft.com/security/For additional information about this issue as it applies to Microsoft Windows NT 4.0, see the following article in the Microsoft Knowledge Base:
ARTICLE-ID: Q166730 TITLE : With Unencrypted Password SP3 Fails to Connect to SMB ServerFor additional information about issues resolved by updates to these components, see the following articles in the Microsoft Knowledge Base:
ARTICLE-ID: Q165402 TITLE : Windows 95 Update to Encrypt Passwords in Memory ARTICLE-ID: Q161100 TITLE : File May Be Truncated When Copied to a Full Network Drive ARTICLE-ID: Q157114 TITLE : "Access Denied" Attempting to Run File on LM/X Server ARTICLE-ID: Q156497 TITLE : Duplicate Print Output on PC-LAN Server from Windows 95 Client ARTICLE-ID: Q140558 TITLE : Deleting Files on Samba Servers May Delete Local Files Instead ARTICLE-ID: Q138249 TITLE : Updated Vredir.vxd Corrects Errors Running Files on LMX ARTICLE-ID: Q160807 TITLE : Cannot Connect to Windows NT Server with Many Shares ARTICLE-ID: Q150215 TITLE : Disabling Automatic Network Shortcut Resolution ARTICLE-ID: Q138014 TITLE : File May Be Truncated to Zero Bytes When Copied Onto Itself ARTICLE-ID: Q136834 TITLE : Error Copying Read-Only Files to Core SMB Server |
Additional query words: 95
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