IE 11 Stands Up to Pwn2Own Exploit Attempt

Browser exploits continue to make news at Pwn2Own, but one that failed stood out in particular.

VANCOUVER – Successful exploits at the Pwn2Own contest get all the glitz, but the rarities are the exploits that fail.

A group of four young South Korean hackers from ASRT, all of them well shy of their thirtieth birthdays, stood in proxy for Jung Hoon Lee. Lee was home fulfilling a military obligation, a promise that kept him from seeing his Internet Explorer 11 exploit come up short Thursday morning.

HP’s Zero Day Initiative, sponsors of the event, said they bought the vulnerability regardless, and worked with the researchers on breaking down the details. The particulars would also be shared with Microsoft as is customary with all bugs purchased by ZDI, sharing them with the affected vendors.

Registrants at Pwn2Own have 30 minutes to demonstrate their exploit and verify it works by executing the calculator application on the underlying system. In this case, Lee’s exploit was chasing down a vulnerability in IE 11 on a fully patched 64-bit Windows 8.1 machine. A successful exploit would have been worth $100,000.

Generally, entrants in Pwn2Own withdraw if there are difficulties with their exploits. On Tuesday, Microsoft rolled out another patch for Internet Explorer. The cumulative rollup, a regular Patch Tuesday update, repaired a zero-day in Internet Explorer 10 being used in targeted attacks, including Operation SnowMan targeting the U.S. Veterans of Foreign Wars and a separate attack on a French aerospace manufacturer. It was not disclosed whether the patch affected the Lee exploit.

The failure of Lee’s exploit was in stark contrast to others demonstrated to that point, including one by German researcher Sebastian Apelt of Siberas who succeeded against IE 11. Apelt’s exploit worked in less than a minute and was good for $100,000. Earlier on Thursday, a pair of Chinese hackers from the Keen Team successfully exploited a zero-day vulnerability in Apple’s Safari browser to gain control of a Macbook running OS X Mavericks. That exploit was worth $65,000 and the members of Keen Team announced they would donate a portion of that to Malaysian charities.

Soon after the IE setback, Pwn2Own regular George Hotz took down Firefox to collect a $50,000 prize. Hotz is perhaps better known for his jailbreaking exploits against the iPhone and the PlayStation gaming console. Hotz’s attack against Firefox was the fourth time zero-days were exploited in the Mozilla browser during the two-day event.

Hackers from French exploit vendor Vupen took down both Internet Explorer and Firefox on Wednesday as part of a $350,000 haul. Vupen also beat Adobe Reader and Flash. On Thursday, Vupen has another exploit for Chrome worth another $100,000. Once the Keen Team popped Safari today, Vupen withdrew its Safari bug. It also withdrew its Java entry on Wednesday.

Vupen founder Chaouki Bekrar said his researchers prepared for two months in advance on Pwn2Own and had little trouble with IE 11 yesterday, using a a use-after-free vulnerability combined with an “object confusion” to bypass the IE sandbox, Bekrar said.

“It’s definitely getting harder to exploit browsers, especially on Windows 8.1,” Bekrar said. “Exploitation is harder and finding zero-days in browsers is harder.”

Vupen’s successful exploit of Firefox on Wednesday also took advantage of a different use-after-free zero day to bypass ASLR and DEP memory protections in Windows. Bekrar said the bug was found through the use of fuzzers against 60 million test cases.

“That proves Firefox has done a great job fixing flaws; the same for Chrome,” Bekrar said. “Chrome has the strongest sandbox, so that’s even more difficult to create exploits for.”

ZDI announced prior to the event it would buy all the Pwn2Own bugs at a price of close to $1.1 million.

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