Google has launched a bold, experimental vulnerability reward program that pays researchers who discover legitimate, critical flaws in its Web applications -- including Google.com, Blogger.com, Orkut.com, and YouTube.com.

Web hacking traditionally has posed some tricky legal challenges for researchers. Google's new program encourages researchers to poke holes in its Web services and pays anywhere from $500 to $3,133.70 for a severe or "clever" vulnerability -- a move experts say could open the door for other cloud-based providers to do the same.

"Google is the first major company to come forward and invite attacks against its online in-production applications," says HD Moore, creator of Metasploit and chief security officer at Rapid7. "While security researchers have spent years testing software applications and reporting the findings, those that decided to take this approach online have faced legal challenges. This is a great precedent for the security community and will hopefully encourage other services providers to take a similar approach."

Google says its Web properties under the program include any that manage or show sensitive, authenticated user data or accounts, but its client apps, such as Picasa, Google Desktop, and Android, are off-limits for now.

The program comes on the heels of a similar program to reward bug finds in its Chromium software, which was started back in January.

Buying Web bugs from researchers is not the norm: HP TippingPoint's Zero Day Initiative, for example, doesn't purchase Web services vulnerabilities because the codebase changes so regularly and rapidly, says Aaron Portnoy, manager of the security research team at HP TippingPoint. "This is interesting because Google is kind of going into some uncharted territory," Portnoy says. "We've seen a lot of vulnerabilities in Facebook or YouTube or Google, but our policy is we don't buy them."

"Google is filling a gap we don't deal with," he adds. "This is nice to see because it means someone is going to be patching these."

The tricky part for Google, however, will be what it does with bugs it decides aren't bounty-worthy. "If they get a submission for one of their Web services and they don't deem it a big deal and don't want to pay out a bounty" nor fix it, then what? Portnoy says. "When you're the affected vendor, you get into some tricky territory."

Some researchers have begun challenging the tradition of disclosing their work for free to vendors. Companies such as Microsoft oppose exchanging currency for bugs, for example. "Researchers deserve getting paid for their work," says Aviv Raff, a researcher and CTO at Seculert, a cloud-based cyberthreat management service provider.

"It's good to see Google really encouraging researchers to search for bugs in their systems and help improve the security of their products and services. The cost of finding and fixing vulnerabilities can be quite high. Partnering with the research and white-hat hacking community can be a responsible and economical win-win for all," says Rick Moy, CEO of NSS Labs.

Google expects most of the accepted bugs will be cross-site scripting, cross-site request forgery, cross-site script inclusion, bypass of authorization controls, and server-side code execution or command injection.

No automated testing tools are allowed, nor are attacks against Google's corporate infrastructure, social engineering and physical attacks, denial-of-service bugs, non-Web application vulnerabilities, SEO blackhat techniques, vulnerabilities in Google-branded websites hosted by third parties, and flaws in any newly acquired technologies by Google, said Google security team members Chris Evans, Neel Mehta, Adam Mein, Matt Moore, and Michal Zalewski in a blog post announcing the new program.

Participants must target only their own accounts or test accounts, Google said, and not try to gain access to another user's data.

As for disclosure: "We believe handling vulnerabilities responsibly is a two-way street. It's our job to fix serious bugs within a reasonable time frame, and we in turn request advance, private notice of any issues that are uncovered. Vulnerabilities that are disclosed to any party other than Google, except for the purposes of resolving the vulnerability (for example, an issue affecting multiple vendors), will usually not qualify. This includes both full public disclosure and limited private release," they said in the post.

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