Crowds of watchers yesterday cheered as Jack successfully demonstrated his technique at the annual Black Hat Conference under way in Las Vegas, attended by around 6000 hackers and security experts.

A director of security research for IOActive, Jack spent more than a year learning to break into standalone ATMs found at service stations, bars and retail establishments.

He found physical keys used to unlock the ATMs were the same for all models. After buying a legitimate ATM , he used the key to unlock a compartment in other ATMs and – via USB – insert a program that commanded the machines to dump their cash on command.

He also hacked into ATMs by exploiting weaknesses in the way ATM makers communicate with the machines over the Internet.

Jack did not give more details because he said the goal of his talk "isn't to teach everybody how to hack ATMs. It's to raise the issue and have ATM manufacturers be proactive about implementing fixes."