How can I get the white beret?

The White Hat (white beret) is a reference to white hat hackers. These are hackers who find an exploit, but rather than abusing it they report the bug to the developer. Specifically bugs in the code. For example, finding a way for a custom cheat client to crash the server and reporting so that it can be fixed. Reporting in-game bugs like an out-of-map exploit is more-so what the Debugger's Beret was intended for, but that became its own problem.