Detections
Analytics

1.5 Ensure Guest Users Are Reviewed on a Regular Basis

Warning! Audit Deprecated

This audit has been deprecated and will be removed in a future update.

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Information

Azure AD is extended to include Azure AD B2B collaboration, allowing you to invite people from outside your organization to be guest users in your cloud account and sign in with their own work, school, or social identities. Guest users allow you to share your company's applications and services with users from any other organization, while maintaining control over your own corporate data.

Work with external partners, large or small, even if they don't have Azure AD or an IT department. A simple invitation and redemption process lets partners use their own credentials to access your company's resources as a guest user.

Guest users in every subscription should be review on a regular basis to ensure that inactive and unneeded accounts are removed.

Rationale:

Guest users in the Azure AD are generally required for collaboration purposes in Office 365, and may also be required for Azure functions in enterprises with multiple Azure tenants. Guest users are typically added outside your employee on-boarding/off-boarding process and could potentially be overlooked indefinitely, leading to a potential vulnerability. To prevent this, guest users should be reviewed on a regular basis. During this audit, guest users should also be determined to not have administrative privileges.

Impact:

Before removing guest users, determine their use and scope. Like removing any user, there may be unforeseen consequences to systems if it is deleted.

NOTE: Nessus has provided the target output to assist in reviewing the benchmark to ensure target compliance.

Solution

From Azure Portal

From Azure Home select the Portal Menu

Select Azure Active Directory

Select Users

Click on Add filter

Select User type

Select Guest from the Value dropdown

Click Apply

Delete all Guest users that are no longer required or are inactive

From Azure CLI
Before deleting the user, set it to inactive using the ID from the Audit Procedure to determine if there are any dependent systems.

az ad user update --id <[email protected]> --account-enabled {false}

After determining that there are no dependent systems delete the user.

Remove-AzureADUser -ObjectId <[email protected]>

From Azure PowerShell
Before deleting the user, set it to inactive using the ID from the Audit Procedure to determine if there are any dependent systems.

Set-AzureADUser -ObjectId '<[email protected]>' -AccountEnabled false

After determining that there are no dependent systems delete the user.

PS C:\>Remove-AzureADUser -ObjectId <[email protected]>

Default Value:

By default no guest users are created.

See Also

https://workbench.cisecurity.org/benchmarks/10624

Item Details

References: CSCv7|16.6, CSCv7|16.8

Plugin: microsoft_azure

Control ID: aa4658ddb9d7bc946af82d0a3b6a10b6c4ccf4c2ce7691bc632edb827e06de62