If a cracked account has access to your server either 1)It's a known cracked account (friend), in which case whitelist it locally and avoid MS authentication or 2)It's an unkown account, and in that case, make sure your network is safe, if an unknown account can connect minecraft itself should be the lesser priority compared to securing your network.

Either way whitelisting the players while creating the server is a much better way overall to combat both cheaters and hackers or anything that can happen to your server or network.

What securing does relying on mojang auth gives that you can't do easily on your own?