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RSA CONFERENCE 2012 -- San Francisco, Calif. -- The major browsers have all made solid strides in security in the past few years, but Chrome's sandbox makes Google's browser a harder target for attackers to exploit with malicious code, four researchers said here in a presentation yesterday.

The group of researchers -- all current or former employees of security consultancy Accuvant -- gave attendees an in-depth tour of their results at the conference, which were published late last year. Some controversy has surrounded the security comparison because Google -- the maker of the Chrome browser -- funded the study.

Microsoft's Internet Explorer and Google's Chrome's countermeasures made both browsers more secure on the metrics used by Accuvant, with Google's browser edging out Microsoft's in sandboxing technology, Shawn Moyer, practice manager for Accuvant, told conference attendees.

"We focused heavily on exploitation mitigation in this paper," Moyer said. "We accepted that users will click on things and the browser will be exploited, but if you have something that you can use to contain the hack, you are going to raise the bar for attackers."

The survey has been criticized by NSS Labs, a security testing firm that came to a different conclusion in a paper last year: Microsoft's SmartScreen URL reputation system helped Internet Explorer catch 96 percent of all malicious Web sites. Google's Chrome came in a distant second place, catching about 13 percent of websites.

At the RSA Conference, the researchers repeatedly stressed that their paper and methods are open. Anyone can review and redo the testing, Moyer argued. Moreover, they also pointed out that they could not replicate NSS Labs' findings. They found all three browsers were equally poor at catching malicious pages.

Chrome distanced itself from other browsers mainly because of its sandbox technology -- a virtual playpen in which the browser runs but cannot impact other applications' data or the operating system. Internet Explorer has some sandboxing, but not as completely as Chrome, the researchers said. A strong sandbox helps keep the operating systems secure because a malicious program that runs inside the sandbox cannot access any system resources outside of the virtual machine.

Sandboxes are important because they help limit or prevent damage when a user inadvertently runs malicious code. "It's the difference between closing a tab versus reinstalling the operating system" because of malicious code, said Paul Mehta, an Accuvant researcher and presenter.

Patching is another area where Google excelled. The researchers analyzed the disclosure and patch timelines of vulnerabilities patched in each browser and found that Google took the shortest amount of time to patch -- 53 days. Mozilla came in second at 158 days and Microsoft took 214 days. Data on vulnerability disclosure was scarce, the researchers said because -- especially in Microsoft's case -- a complete timeline was generally not available.

Google and Firefox have an advantage in patching because they are standalone browsers, while Microsoft has to deal with the tight integration of Internet Explorer with the Windows operating system, said Chris Valasek, senior research scientist with software security firm Coverity. Valasek has originally worked on the project while employed at Accuvant.

"Internet Explorer is quite ingrained into the Windows operating system," Valasek said. "Therefore there is a lot more QA that has to be done for the browser. You don't want to fix a vulnerability and break stability with the entire operating system."

While Google Chrome does well with its strong sandbox and patching, Microsoft has done a solid job of hardening Internet Explorer against a common type of attack that can bypass two major operating-system countermeasure: data-execution protection and address space layout randomization. The attack, known as JIT spraying, uses the just-in-time compilation of a runtime language such as Javascript to circumvent an operating system's defenses.

It's such as popular technique that every piece of software should implement countermeasures. Microsoft created the most complete set of countermeasures in Internet Explorer, with Google having a subset of preventative measures, the researchers said.

"A big push right now is to harden software against exploits so that the cost of exploitation is increased," Mehta said. "Software that does not implement JIT hardening actually decreases the cost of exploitation."

In the end, if given a critical flaw that affected all three browsers, the researchers would likely attempt to exploit it first on Firefox because its easiest.

"If we had the same vulnerability in every browser, we would not pick Chrome to exploit," Valasek said.

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