One of the biggest security concerns I used to chat about with geeky network friends in quiet whispers behind closed doors, was about the baseband radio software in cell phones.
This is the lowest level of software embedded in the phone. It is responsible for establishing and maintaining connections to the cell tower, for example. But it is basically only secured through its obscurity. Nobody really thinks about it, and nobody was ever gonna build their own cellphone tower to exploit such a weakness (cough, cough, Stingray, coughcoughcough), so it was always a hypothetical that we just kinda hoped never got exploited.
Because imagine every cellphone in a city, for example, suddenly trying to connect to a single business. (Via any connection, phone, internet, whatever.)
Nobody is going to be able to sustain an attack of that magnitude.
And 90% of the people with the cell phones won't even know their phone is doing it.
And there would be almost no way to stop it without simply taking down the entire cellular network for the city.
Think that through for a moment, and you can see why we only talked about this type of attack in hushed whispers behind closed doors.
Well... that vulnerability has been established. And published.
Whoops.