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Microsoft network client: Send unencrypted password to third-party SMB servers

Published: November 15, 2012

Updated: November 15, 2012

Applies To: Windows 7, Windows Server 2003, Windows Server 2008, Windows Server 2008 R2, Windows Vista, Windows XP

This security policy reference topic for the IT professional describes the best practices, location, values, policy management and security considerations for this policy setting.

The Server Message Block (SMB) protocol provides the basis for file and print sharing and many other networking operations, such as remote Windows administration. This policy setting allows or prevents the SMB redirector to send plaintext passwords to a non-Microsoft server service that does not support password encryption during authentication.

  • Enabled

    The Server Message Block (SMB) redirector is allowed to send plaintext passwords to a non-Microsoft server service that does not support password encryption during authentication.

  • Disabled

    The Server Message Block (SMB) redirector only sends encrypted passwords to non-Microsoft SMB server services. If those server services do not support password encryption, the authentication request will fail.

  • Not defined

  1. It is advisable to set Microsoft network client: Send unencrypted password to connect to third-party SMB servers to Disabled. Some old applications and operating systems (such as MS-DOS, Windows for Workgroups 3.11, and Windows 95) might not be able to communicate with the servers in your organization through the SMB protocol.

GPO_name\Computer Configuration\Windows Settings\Security Settings\Local Policies\Security Options

The following table lists the actual and effective default values for this policy. Default values are also listed on the policy’s property page.

 

Server type or GPO Default value

Default Domain Policy

Not defined

Default Domain Controller Policy

Not defined

Stand-Alone Server Default Settings

Disabled

DC Effective Default Settings

Disabled

Member Server Effective Default Settings

Disabled

Client Computer Effective Default Settings

Disabled

There are no differences in this policy between operating systems beginning with Windows Server 2003.

This section describes features and tools that are available to help you manage this policy.

None. Changes to this policy become effective without a computer restart when they are saved locally or distributed through Group Policy.

This section describes how an attacker might exploit a feature or its configuration, how to implement the countermeasure, and the possible negative consequences of countermeasure implementation.

If you enable this policy setting, the server can transmit plaintext passwords across the network to other computers that offer SMB services. These other computers might not use any of the SMB security mechanisms that are included with Windows Server 2003 or later.

Disable the Microsoft network client: Send unencrypted password to connect to third-party SMB servers setting.

Some old applications and operating systems (such as MS-DOS, Windows for Workgroups 3.11, and Microsoft Windows 95) may not be able to communicate with the servers in your organization by means of the SMB protocol.

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