Pro Arena is made of servers build by users (that have enterprise account). The servers from Pro Arena are suppose to be not vulnerable. This because in Pro Arena we want to mimic the real Internet where servers should not be vulnerable. However there are vulnerable servers. Why is this important (real servers -- not vulnerable by design)? Because if you want to get the real thing of a real hacker, this is what real hackers confront with. They have to perform real good reconnaissance and find a way in.
However in the new up coming version of CTF365  there will be specially designed challenges (what you are looking for). If all in place, we should launch by the end of January 2017.