They basically create a treasure map (Tasmania jones is the clue) and lock that map in a sealed volt that needs 5 keys and only opens on the right day.
The exams themselves are buried in a non-descript location by a team of echidna's sworn to secrecy.
No but really they probably sign non-disclosure agreements and they're probably kept in sealed boxes or other things like that. It's just like election ballots, they have to be sealed in a certain way i believe to help detect tampering etc. Why would someone leak it? They're probably already senior in the organisation if they're in a position to just simply grab a bunch of them. They'd probably get found out and lose their job. What do they gain from leaking it? It's hard to see what. If it was leaked, its in the interests of those who have a copy to not tell anyone else so they could actually use it..
For these reasons, its highly unlikely you'll ever see one.