New Post: Get Media File GUID Via Admin Portal

For @wysocki's suggestion append a PermissionTypes attribute to the MessageBoxAction, like this:

<MessageBoxAction 
          Label="GUID" MessageBoxTitle="${C1:Data:Composite.Data.Types.IMediaFile:FileName}" 
          MessageBoxMessage="${C1:Data:Composite.Data.Types.IMediaFile:Id}" 
          PermissionTypes="administrate" /> 

See https://docs.composite.net/Console/Tree-Schema-Definition-Reference/MessageBoxAction

For @burningice's suggestion, edit the source code of the GetMediaLinkActionToken and GetPageLinkActionToken classes and limit the permission type to only "PermissionType.Administrate" (removing "PermissionType.Edit") - around line 17,19 in both classes.