The connectors in TAO catalog use RF to make that impossible without unusual spectrum analyzers. I did that, too. Another trick is covert channels to make it invisible in network traffic. Covert channel analysis is mandated in high assurance specs but almost nobody does it.

Anyway, you're not going to see a switch subverted by pro's in action. They won't blow that cover. They'll use it to facilitate a normal attack and plant evidence it came through a normal vector. That's how subversion works at pro level.