| name | cis-azure-foundations-5.15 |
| description | Ensure 'Guest users access restrictions' is set to 'Guest user access is restricted to properties and memberships of their own directory objects' |
| category | cis-azure-foundations |
| version | 5.0.0 |
| author | cyberstrike-official |
| tags | ["cis","azure","identity","guest-access","external-identities","least-privilege"] |
| cis_id | 5.15 |
| cis_benchmark | CIS Microsoft Azure Foundations Benchmark v5.0.0 |
| tech_stack | ["azure"] |
| cwe_ids | [] |
| chains_with | ["cis-azure-foundations-5.16"] |
| prerequisites | [] |
| severity_boost | {} |
Ensure '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.
Rationale
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:
- Guest users have the same access as members (most inclusive),
- Guest users have limited access to properties and memberships of directory objects (default value),
- 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".
Impact
This may create additional requests for permissions to access resources that administrators will need to approve. Some services (Forms, Project, Yammer, Planner in SharePoint) without current support might have compatibility issues with the new guest restriction setting.
Audit Procedure
Using Azure Portal
- From Azure Home select the Portal Menu
- Select
Microsoft Entra ID
- Under
Manage, select External Identities
- Select
External collaboration settings
- Under
Guest user access, ensure that Guest user access restrictions is set to Guest user access is restricted to properties and memberships of their own directory objects
Using PowerShell
Connect-MgGraph
(Get-MgPolicyAuthorizationPolicy).GuestUserRoleId
If the GuestUserRoleId property does not equal 2af84b1e-32c8-42b7-82bc-daa82404023b then it is not set to most restrictive.
Expected Result
Guest user access restrictions should be set to Guest user access is restricted to properties and memberships of their own directory objects. The GuestUserRoleId should equal 2af84b1e-32c8-42b7-82bc-daa82404023b.
Remediation
Using Azure Portal
- From Azure Home select the Portal Menu
- Select
Microsoft Entra ID
- Under , select
