2.3.27.5 Ensure 'Allow Basic Authentication prompts from network proxies' is set to 'Disabled'

Information

Apps such as Word and Excel allow users to use Basic authentication to connect to resources on web servers by sending usernames and passwords with each request. These credentials are often stored on the servers, making it easier for attackers to capture them and reuse them against other endpoints or services.

The recommended state for this setting is: Disabled.

Note: This policy setting only applies to subscription versions of Office, such as Microsoft 365 Apps for enterprise, and to subscription versions of Project and Visio.

Note 2: This change doesn't affect Outlook connecting to on-premises Exchange Server using Basic authentication. This change also doesn't affect Outlook connecting to Exchange Online using Basic authentication. There is a separate effort to deprecate Basic authentication with Exchange Online. For more information, see Basic authentication deprecation in Exchange Online

Rationale:

Basic authentication is an outdated industry standard and doesn't support more robust security features, such as multifactor authentication. The threats posed by it have only increased and there are better and more effective user authentication alternatives. For example, modern authentication, which supports multifactor authentication, smart cards, and certificate-based authentication.

Impact:

None - this is the default behavior.

Solution

To establish the recommended configuration via GP, set the following UI path to Disabled:

User Configuration\Administrative Templates\Microsoft Office 2016\Security Settings\Allow Basic Authentication prompts from network proxies

Default Value:

Disabled

See Also

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

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6, 800-53|CM-7, CSCv7|9.2

Plugin: Windows

Control ID: 5da728a55c59122c4189a1044533447a67409a232534ffaf5a8d1742f95a36f3