6.2 Block OneDrive for Business sync from unmanaged devices

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Information

You should prevent company data from OneDrive for Business from being synchronized to non-corporate managed devices.

Rationale:

Unmanaged devices pose a risk, since their security cannot be verified. Allowing users to sync data to these devices, takes that data out of the control of the organization. This increases the risk of the data either being intentionally or accidentally leaked.

Impact:

Enabling this feature will prevent users from using the OneDrive for Business Sync client on devices that are not joined to the domains that were defined.

NOTE: Nessus has not performed this check. Please review the benchmark to ensure target compliance.

Solution

To block the sync client on unmanaged devices, use the Microsoft 365 Admin Center:

Navigate to Microsoft 365 administration portal (https://admin.microsoft.com), Click on All Admin Centers and then Show All, then SharePoint.

Now click Settings followed by OneDrive - Sync

Check the Allow syncing only on computers joined to specific domains

Use the Get-ADDomain PowerShell command to obtain the GUID from each domain then add them to the box.

Click Save

To block the sync client on unmanaged devices, you can also use SharePoint Online PowerShell:

Connect to SharePoint Online using Connect-SPOService

Run the following PowerShell command and provide the DomainGuids from the Get-AADomain command:

Set-SPOTenantSyncClientRestriction -Enable -DomainGuids '786548DD-877B-4760-A749-6B1EFBC1190A; 877564FF-877B-4760-A749-6B1EFBC1190A'

NOTE: Utilize the -BlockMacSync:$true parameter if you are not using conditional access to ensure Macs cannot sync.

Default Value:

This feature is not enabled by default.

See Also

https://workbench.cisecurity.org/files/3729