If you can do it, chances are an attacker can, too. I prefer hardware that won't load unsigned software in such places.
I don't know the solution, but the black box approach we have right now I do not like. As a pilot this is a bit weird for me to say because those systems are also completely proprietary as well, full on black box - and not the d/v recording type. And I'm even wondering if that's overdue for a change as well.