And really, would that be such a horrible thing? Yes. Yes it would. It would be a horrible thing.

A team of researchers recently presented the results of some work they did involving some time in a basement, $2500, and no previous experience working with the type of industrial control systems and programmable logic controllers the prison used. Basically, if they can get some malware loaded on to the prison computer system then the system can be remotely controlled. Doors could be opened.

This from Ars Technica:

The researchers began their work after Strauchs was called in by a warden to investigate an incident in which all the cell doors on one prison’s death row spontaneously opened. While the computers that are used for the system control and data acquisition (SCADA) systems that control prison doors and other systems in theory should not be connected to the Internet, the researchers found that there was an Internet connection associated with every prison system they surveyed. In some cases, prison staff used the same computers to browse the Internet; in others, the companies that had installed the software had put connections in place to do remote maintenance on the systems.

So steer them to a malware site and boom. Or, said the researchers, the malware could be loaded through a flash drive like with the Stuxnet worm. All it would take then is one smuggled flash drive from an inmate or some prison employee screwing up.