At this year's Black Hat conference, Barnaby Jack, director of security testing at IOActive, demonstrated that it's possible to hack into an ATM.
CNET News reports that Jack unearthed a number of vulnerabilities in ATMs. His demonstration involved ATMs manufactured by Tranax Technologies and Triton. Says Jack:
Every ATM I've looked at, I've found a game-over vulnerability that allows an attacker to get cash from the machine ... I've looked at four ATMs. I'm four for four.
Both Tranax and Triton have patched the security vulnerabilities since it was brought to their attention a year ago. While Jack's research focused on standalone and hole-in-the-wall ATMs, he did not rule out the idea that bank ATMs could have similar vulnerabilities, though he hasn't examined them yet, notes Wired News.