Pwn2Own 2012: Google Chrome browser sandbox first to fall

Exploit writers at VUPEN take special pleasure in attacking Google's Chrome browser, using a pair of zero-day flaws to defeat the browser's heralded sandbox.
Written by Ryan Naraine, Contributor

VANCOUVER -- At last year's CanSecWest Pwn2Own hacker contest, Google Chrome and Mozilla Firefox were the only browsers left standing.   This year, Chrome was the first to fall, thanks to an impressive exploit from a team of French hackers.

VUPEN, the controversial company that sells vulnerabilities and exploits to government customers, deliberately took aim at Chrome this year to send a simple message: no software is unbreakable if hackers have enough motivation to prepare and launch an attack.

VUPEN co-founder and head of research Chaouki Bekrar and his team used a pair of zero-day vulnerabilities to take complete control of a fully patched 64-bit Windows 7 (SP1) machine.   As part of the new competition format, VUPEN will earn 32 points for the successful Chrome exploit.

[ SEE: Charlie Miller skipping Pwn2Own as new rules change hacking game ]

In an interview, Bekrar said his team worked for about six weeks to find the vulnerabilities and write the exploits.  "We had to use two vulnerabilities. The first one was to bypass DEP and ASLR on Windows and a second one to break out of the Chrome sandbox."

Bekrar declined to say if any of the exploits targeted third-party code in the browser.  "It was a use-after-free vulnerability in the default installation of Chrome," he said. "Our exploit worked against the default installation so it really doesn't matter if it's third-party code anyway."

Last year, VUPEN released a video to demonstrate a successful sandbox escape against Chrome but Google challenged the validity of that hack, claiming it exploited third-party code, believed to be the Adobe Flash plugin.

[ SEE: CanSecWest Pwnium: Google Chrome hacked with sandbox bypass ]

At Pwn2Own this year, Bekrar's team came equipped for zero-day flaws for all four major browsers -- Google Chrome, Microsoft Internet Explorer, Apple Safari and Mozilla Firefox -- but he said the decision to go after Chrome first was a deliberate tactic.

"We wanted to show that Chrome was not unbreakable. Last year, we saw a lot of headlines that no one could hack Chrome.  We wanted to make sure it was the first to fall this year," he said.

During the hack,  Bekrar created a web page booby-trapped with his exploit.  Once the target machine visited the page, the exploit ran and opened the Calculator (calc.exe) app outside of the sandbox."

"There was no user interaction, no extra clicks.  Visit the site, popped the box."

VUPEN will sell the rights to one of the zero-day vulnerabilities but the company says it won't give up the sandbox escape. "We are keeping that private, keeping it for our customers."

Even as he basked in the glory of defeating the highly touted Chrome sandbox, Bekrar was very complimentary of the work done by Google's security team to add anti-exploit mechanisms into the browser.

"The Chrome sandbox is the most secure sandbox out there. It's not an easy task to create a full exploit to bypass all the protections in the sandbox.   I can say that Chrome is one of the most secure browsers available."

"This just shows that any browser, or any software, can be hacked if there is enough motivation and skill," he added.

Editorial standards