This may be the shortest article of them all but no less unimportant. I have had trouble finding this when I have needed it. The canned Rbac Role script still exisit in 2013 Exchange. Here are the steps to carry it out:
•Launch Exchange Management Shell
•Run “Add-pssnapin microsoft*”
•Close and re-open Exchange Management Shell
This completes the reset of RBAC default permissions. Have a great day!