Reminds me of LEDs used to extract data out of airgapped networks: https://threatpost.com/blinking-router-leds-leak-data-from-air-gapped-networks/126199/ but different because that one requires software within the airgapped network to exfiltrate.

Didn’t there used to be network equipment that was vulnerable to data exfil from data status lights, or did I dream that up? Most data LEDs now just consistently blink.