IoT devices poke holes in any perimeter
Internet of Things (IoT) devices are now some of the most prolific network-enabled assets on the planet. Over 6 billion of these devices are known to be currently connected to the internet as of 2019. All these 6 billion devices are web-enabled, app-enabled, require passwords for authentication, and are usually developed and built in nations that are known to have adversarial ties to government hacking organizations. In other words, they are guaranteed to have some level of insecurity from the day they roll off the manufacturing floor. And most, if not almost all, enterprises have some form of an IoT device in their network somewhere.
Whether it's a smart TV, smart thermostat, wireless printer, internet-enabled camera, or some other device somewhere in an enterprise, it is a certainty that an IoT device exists in that infrastructure.
The use of proprietary wireless signals and protocols within IoT devices is the main avenue...