U.S. researchers say a prototype firewall can keep hackers from interfering with wireless medical devices such as pacemakers and insulin-delivery systems.

A team of scientists from Purdue and Princeton universities had previously demonstrated how medical devices could be hacked, potentially leading to catastrophic consequences.

"You could imagine all sorts of scary possibilities," Anand Raghunathan, a Purdue professor of electrical and computer engineering, said. "What motivated us to work on this problem was the ease with which we were able to break into wireless medical systems."

The potentially vulnerable devices include pacemakers and continuous glucose monitoring and insulin delivery systems for patients with diabetes, now in use by hundreds of thousands of people, a Purdue release said Thursday.

Brain implants under development to control epilepsy and "smart prosthetics" operated using electronic chips also could be hacked, Princeton researcher Niraj K. Jha said.

While risk of devices being hacked may be low, he said, security measures are merited before "attacks" in the lab are replicated on real systems.

The researchers have created a prototype system called MedMon, for medical monitor, which acts as a firewall to prevent hackers from hijacking the devices.

"It's an additional device that you could wear, so you wouldn't need to change any of the existing implantable devices," Raghunathan said. "This could be worn as a necklace, or it could be integrated into your cellphone, for example."