Users hacking achievements / leaderboards

Since reporting achievements and leaderboard scores are exposed to script and I have implemented them in script on my app, I'm starting to get concerned that it would be super easy for users to open my app take a look at the scripts and report whatever score they want to the leaderboards.

Is there anything preventing this scenario from occurring? Apps aren't encrypted right? I imagine that Apple also doesn't checksum apps that are reporting leaderboards?