Computer-security researchers are focusing attention on smart meters in part because utilities have been installing them by the millions. (The Obama stimulus bill provided $4.5 billion for "smart grid" projects; the European Union has mandated a switch-over to smart meters by 2022.)

Why they are targets:

Because smart meters register every tiny up and down in energy use, they are, in effect, monitoring every activity in the home. ... Like the computer on my home-office desk, the smart-meter computer in my basement is vulnerable to viruses, worms, and other Internet perils.