Why? Both the Israeli Intelligence Heritage museum and the Vault 5 leaks specifically show hardware implants that are intended to be inserted into cables like display, HID and USB cables.

Building a network tap into a CAT5 cable isn’t that hard you just need to essentially modulate the traffic into RF and have another implant near by that can intercept the radio signals.

We live in a day where we have demonstratable side channels attacks against RSA keys by listening to how a laptop squeeks when it’s under load and you think building a chip into a cable is a stretch?

Heck I have one cable like that atm which is a converter from a model M keyboard to a USB you can’t see the converter IC it’s built into the RJ45 connector the keyboard originally used without any additional bulk.