I have mine outside, I’m not enough of a security expert to trust them inside yet. Don’t want anyone seeing me running around in my underwear doing a Tom Cruise scene from risky business.
Practically, if the system isn’t connected to the Internet and is either using analog cameras over coax, encrypted WiFi, or Ethernet, there’s zero chance of that.
Only connect the system to the ‘net if you’re traveling and want remote access to it — an Ethernet cable is easy to unplug.