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Computerworld - Apple today patched a critical Mac OS X vulnerability used by a security researcher three weeks ago to win $10,000 for hacking Safari at the Pwn2Own contest.

The patch is the second resulting from the fourth annual Pwn2Own, which was held at the CanSecWest security conference in Vancouver, British Columbia March 24-26.

On the first day of the contest, Charlie Miller, an analyst at Baltimore-based Independent Security Evaluators, hacked Safari running on Mac OS X 10.6, aka Snow Leopard. Miller is the only researcher to ever win three times at Pwn2Own.

Today, Miller confirmed that the vulnerability Apple patched was the one he used last month to earn a $10,000 prize. "That must be it," he said. "I haven't given them any other bugs."

In fact, Miller refused to divulge additional bugs he'd found in Apple's operating system during the conference, instead giving a presentation on how he used "dumb fuzzing" techniques to uncover more than 20 exploitable vulnerabilities in Adobe, Apple and Microsoft software. During the presentation, Miller argued that security is a "broken record," and said that it was more effective in the long run to simply show the companies how to replicate his work.

"What I can do is tell them how to find these bugs, and do what I did. That might get them to do more fuzzing," Miller said in a March interview. That, he maintained, would result in more secure software.

Apple slashed the time it took to patch Miller's Pwn2Own bug by more than half compared to last year, when he also hacked Mac OS X at the contest. In 2009, Apple took 55 days to fix the flaw; this year, it needed just 21 days.

"That's pretty fast," said Miller today. "It's not like there's a rush. I didn't tell anyone about the bug."

Pwn2Own rules require researchers to keep quiet until their vulnerabilities are patched. 3Com TippingPoint, which sponsors the contest, purchases all rights to the vulnerability and exploit research, which it turns over to the vendor. TippingPoint also stays mum until a patch is released.

"If they had taken four months or more, it wouldn't have mattered," Miller added.

According to Apple, the vulnerability Miller exploited was in ATS (Apple Type Services), a font renderer included with Mac OS X. "Viewing or downloading a document containing a maliciously crafted embedded font may lead to arbitrary code execution," Apple said in the advisory accompanying the one-patch update. "An unchecked index issue exists in Apple Type Services' handling of embedded fonts."

Miller exploited ATS through Apple's Safari browser, which accesses ATS code libraries to draw text. Last year, Miller also exploited ATS at Pwn2Own.