The attacks demonstrated Wednesday targeted standalone ATMs. But they could potentially be used against the ATMs operated by mainstream banks. (Tony Smyth/CBC)

A hacker has discovered a way to force ATMs to disgorge their cash by hijacking the computers inside them.

The attacks demonstrated Wednesday in Las Vegas targeted standalone ATMs. But they could potentially be used against the ATMs operated by mainstream banks.

Criminals have long known that ATMs aren't tamperproof.

There are many types of attacks in use today, ranging from sophisticated to foolhardy: installing fake card readers to steal card numbers, hiding tiny surveillance cameras to capture PIN codes, covering the dispensing slot to intercept money and even hauling the ATMs away with trucks in hopes of cracking them open later.

Computer hacker Barnaby Jack spent two years tinkering in his Silicon Valley apartment with ATMs he bought online. These were standalone machines, the type seen in front of convenience stores, rather than the ones in bank branches.

His goal was to find ways to take control of ATMs by exploiting weaknesses in the computers that run the machines.

He showed off his results at the Black Hat conference in Las Vegas, an annual gathering devoted to exposing the latest computer-security vulnerabilities.

His attacks have wide implications because they affect multiple types of ATMs and exploit weaknesses in software and security measures that are used throughout the industry.

His talk was one of the conference's most widely anticipated, as it had been pulled a year ago over concerns that fixes for the ATMs wouldn't be in place in time. He used the extra year to craft more dangerous attacks.

Jack, who works as director of security research for Seattle-based IOActive Inc., showed in a theatrical demonstration two ways he can get ATMs to spit out money:

• He found that the physical keys that came with his machines were the same for all ATMs of that type made by that manufacturer. He used his key to unlock a compartment in the ATM that had standard USB slots. He then inserted a program he had written into one of them, commanding the ATM to dump its vaults.
• Jack also hacked into ATMs by exploiting weaknesses in the way ATM makers communicate with the machines over the internet. He said the problem is that outsiders are permitted to bypass the need for a password.

Jack 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."