Ok. Maybe I misunderstood you. If you are thinking of having the tests leak and people just finding solutions on Google I'm just thinking of dynamically generating the problem. How about 3 characters missing from the config file for apache at random. You have to understand what is required and then try to fix it. Does this solve your case?

I had similar idea to your and found no solution to problem of copy-pasting. Good problem sets are hard to create but their solutions are easy to copy. Moreover, this is the good practice to try to solve solution locally, then copy-paste solution to target server.

I hope, you will find a solution for that.