A hacker managed to break into a Mac and win a $10,000 prize as part of a contest started at the CanSecWest security conference in Vancouver.

In winning the contest, he exposed a hole in Safari, Apple's browser. "Currently, every copy of OS X out there now is vulnerable to this," said Sean Comeau, one of the organizers of CanSecWest.

The conference organizers decided to offer the contest in part to draw attention to possible security shortcomings in Macs. "You see a lot of people running OS X saying it's so secure, and frankly, Microsoft is putting more work into security than Apple has," said Dragos Ruiu, the principal organizer of security conferences including CanSecWest

Initially, contestants were invited to try to access one of two Macs through a wireless access point while the Macs had no programs running. No attackers managed to do so, and so conference organizers allowed participants to try to get in through the browser by sending URLs via e-mail.

Dino Dai Zovi, who lives in New York, sent along a URL that exposed the hole. Because the contest was only open to attendees in Vancouver, he sent it to a friend who was at the conference and forwarded it on.

The URL opened a blank page but exposed a vulnerability in input handling in Safari, Comeau said. An attacker could use the vulnerability in a number of ways, but Dai Zovi used it to open a back door that gave him access to anything on the computer, Comeau said.

The vulnerability won't be published. 3Com's TippingPoint division, which put up the cash prize, will handle disclosing it to Apple.

The prize for the contest was originally one of the Macs. But on Thursday evening, TippingPoint put up the cash award, which may have spurred a wider interest in the contest.

One reason Macs haven't been much of a target for hackers is that there are fewer to attack, said Terri Forslof, manager of security response for TippingPoint. "It's an incentive issue. The Mac is not as widely deployed of a platform as, say, Windows," she said. In this case, the cash may have provided motivation.

The contest was a chance for hackers to demonstrate techniques they may have boasted about. "I hear a lot of people bragging about how easy it is to break into Macs," Ruiu said.

Some attendees didn't think it was a coincidence that on late Thursday Apple released a patch for 25 vulnerabilities in OS X.

Macs haven't been targets for hackers and malicious code writers nearly to the degree that Windows machines have historically. That's in part because there are fewer Macs in use, thus making the potential impact of malicious code smaller than on the more widely used PCs.

Also, Apple is "extremely litigious when people do find stuff," noted Theo de Raadt, OpenBSD project leader and an attendee at the conference. He suspects that will backfire on Apple, which could begin to "look evil" if hackers begin to publish potentially threatening letters from the company.

This story was updated on April 20, 2007