Control: 1.15 Ensure That 'Guest users access restrictions' is set to 'Guest user access is restricted to properties and memberships of their own directory objects'

Description

Limit guest user permissions.

Limiting guest access ensures that guest accounts do not have permission for certain directory tasks, such as enumerating users, groups or other directory resources, and cannot be assigned to administrative roles in your directory. Guest access has three levels of restriction.

1. Guest users have the same access as members (most inclusive),
2. Guest users have limited access to properties and memberships of directory objects (default value),
3. Guest user access is restricted to properties and memberships of their own directory objects (most restrictive).

The recommended option is the 3rd, most restrictive: "Guest user access is restricted to their own directory object".

Remediation

From Azure Portal

1. From Azure Home select the Portal Menu
2. Select Azure Active Directory
3. Then External Identities
4. Select External collaboration settings
5. Under Guest user access, change Guest user access restrictions to be Guest user access is restricted to properties and memberships of their own directory objects

From Powershell

1. From a Powershell session enter Set-AzureADMSAuthorizationPolicy - GuestUserRoleId '2af84b1e-32c8-42b7-82bc-daa82404023b'
2. Check that the setting was applied by entering GetAzureADMSAuthorizationPolicy
3. Make certain that the GuestUserRoleId is equal to the earlier entered value of 2af84b1e-32c8-42b7-82bc-daa82404023b.

Default Value

By default, Guest user access restrictions is set to Guest user access is restricted to properties and memberships of their own directory objects.