Imagine purchasing a new Rovio robot. This wheeled mobile robot sports a webcam and can be accessed easily through the internet. Often these and other robots are bought as toys, used by the owners to check on their home during a vacation, perhaps for teleconferencing, or to check on an elderly loved one.
Now imagine a malevolent hacker from Russia or China, or your next door neighbor, or a even stalker gaining access to this robot. Now they have free access to your home, roving about checking to see if the owner is home, spying on your children, or perhaps taking embarrassing video of you or your family. What if the robot is commanded to break items in your home, hide your keys, or drive under the feet of granny to harm her? Millions of these robots have been sold, meaning they are quite ubiquitous and therefore prime targets of malicious hackers.
Source: IEEE Spectrum blog.