Hacks occur to due bugs in software. Theoretically, one could write bug-free software. Practically, this is very hard for any non-trivial software. For example

Hacks occur to due bugs in software. Theoretically, one could write bug-free software. Practically, this is very hard for any non-trivial software. For example, a while loop code in a Turing Machine is unhackable; the state repeats forever.