Sure, the backdoor could have e.g. injected an libav exploit into a video file to re-backdoor my system when I watch it... that's too paranoid for me. I don't

Sure, the backdoor could have e.g. injected an libav exploit into a video file to re-backdoor my system when I watch it... that's too paranoid for me. I don't backup the whole system, just a specific list of things in /home.