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3.3 Set 'Select the authentication with Exchange server.' to 'Enabled:Kerberos/NTLM Password Authentication'

Information

This policy setting controls which authentication method Outlook uses to authenticate with
Microsoft Exchange Server. Note - Exchange Server supports the Kerberos authentication
protocol and NTLM for authentication. The Kerberos protocol is the more secure
authentication method and is supported on Windows 2000 Server and later versions.
NTLM authentication is supported in pre-Windows 2000 environments. If you enable this
policy setting, you can choose from three different options for controlling how Outlook
authenticates with Microsoft Exchange Server- - Kerberos/NTLM password authentication.
Outlook attempts to authenticate using the Kerberos authentication protocol. If this
attempt fails, Outlook attempts to authenticate using NTLM. This option is the default
configuration. - Kerberos password authentication. Outlook attempts to authenticate using
the Kerberos protocol only. - NTLM password authentication. Outlook attempts to
authenticate using NTLM only. If you disable or do not configure this policy setting, Outlook
will attempt to authenticate using the Kerberos authentication protocol. If it cannot
(because no Windows 2000 or later domain controllers are available), it will authenticate
using NTLM. The recommended state for this setting is- Enabled-Kerberos/NTLM Password
Authentication.

*Rationale*

Exchange Server supports the Kerberos authentication protocol and NTLM for
authentication. The Kerberos protocol is the more secure authentication method and is
supported on Windows 2000 Server and later versions. NTLM authentication is supported
in pre-Windows 2000 environments. By default, Outlook 2010 will attempt to authenticate
using the Kerberos authentication protocol. If it cannot (because no Windows 2000 or later
domain controllers are available), it will authenticate using NTLM.

Solution

To implement the recommended configuration state, set the following Group Policy setting
to Enabled.


User Configuration\Administrative Templates\Microsoft Outlook 2010\Account
Settings\Exchange\Authentication with Exchange Server\Authentication with Exchange
ServerThen set the Select the authentication with Exchange server. option to
Kerberos/NTLM Password Authentication.

Impact-The recommended value for this setting in the Microsoft baselines enforces the default
configuration, and is therefore unlikely to cause significant usability issues for most users.4 Least Privilege and Segregation of Duty

See Also

https://workbench.cisecurity.org/files/530

Item Details

Category: IDENTIFICATION AND AUTHENTICATION

References: 800-53|IA-5(1)(c)

Plugin: Windows

Control ID: 6a01353aad7036745a463102b148268816917f7146a8c7ad2425abbd7447181d