5.1.6.3 (L2) Ensure guest user invitations are limited to the Guest Inviter role

Information

By default, all users in the organization, including B2B collaboration guest users, can invite external users to B2B collaboration. The ability to send invitations can be limited by turning it on or off for everyone, or by restricting invitations to certain roles.

The recommended state for guest invite restrictions is Only users assigned to specific admin roles can invite guest users

Restricting who can invite guests limits the exposure the organization might face from unauthorized accounts.

Solution

To remediate using the UI:

- Navigate to Microsoft Entra admin center

https://entra.microsoft.com/

.
- Click to expand Identity > External Identities select External collaboration settings
- Under Guest invite settings set Guest invite restrictions to Only users assigned to specific admin roles can invite guest users

To remediate using PowerShell:

- Connect to Microsoft Graph using Connect-MgGraph -Scopes "Policy.ReadWrite.Authorization"
- Run the following command:

Update-MgPolicyAuthorizationPolicy -AllowInvitesFrom 'adminsAndGuestInviters'

Note: The more restrictive position of the value will also pass audit, it is however not required.

Impact:

This introduces an obstacle to collaboration by restricting who can invite guest users to the organization. Designated Guest Inviters must be assigned, and an approval process established and clearly communicated to all users.

See Also

https://workbench.cisecurity.org/benchmarks/17682

Item Details

Category: ACCESS CONTROL, IDENTIFICATION AND AUTHENTICATION

References: 800-53|AC-1, 800-53|AC-2, 800-53|IA-4, 800-53|IA-5, CSCv7|13.1

Plugin: microsoft_azure

Control ID: 9d31bdb39fca325aad987d8e144823ab69d9bb20e872ecf56f78afb936e4e79c