2.5.1.2.1 Ensure 'Authentication with Exchange server' is set to 'Enabled: Kerberos 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.

Policy setting options for controlling how Outlook authenticates with Microsoft Exchange Server:

Kerberos Password Authentication - Outlook attempts to authenticate using the Kerberos protocol only.

Warning When connecting to Office 365, this setting must be set to Disabled.

The recommended state for this setting is: Enabled: Kerberos 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 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.

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.

Warning: Testing of this setting is necessary before deployment as it could cause interruptions in service.

Solution

To establish the recommended configuration via GP, set the following UI path to Enabled: Kerberos/NTLM Password Authentication:

User Configuration\Administrative Templates\Microsoft Outlook 2016\Account Settings\Exchange\Authentication with Exchange Server

Default Value:

Kerberos/NTLM Password Authentication (Outlook will attempt to use Kerberos then NTLM.)

See Also

https://workbench.cisecurity.org/benchmarks/12129

Item Details

Category: SYSTEM AND SERVICES ACQUISITION

References: 800-53|SA-15

Plugin: Windows

Control ID: db15ebe368dce154886d90e0067ca365570a3d99b9e0321040a304f7af476cc2