Google's Chrome browser may have been designed with security in mind, but that hasn't immunized it from security concerns.

Robert "RSnake" Hansen, CEO of SecTheory, a computer security consulting firm, has identified a vulnerability in Chrome that allows JavaScript code to execute when a user views the source code of a Web page using the view-source: directive.

Hansen's blog post about the vulnerability includes a proof-of-concept Web link that, for Chrome users, triggers the flaw and uses JavaScript to present a dialog box that says, "If you can see this, use another browser...seriously."

While any link can trigger JavaScript in this way, this particular issue could provide a building block for a social engineering attack against a Web developer.

Google is planning to fix the issue shortly. "We believe this behavior does not introduce any particular risk for the vast majority of users who do not use view-source: to browse Web pages," said a company spokesperson in an e-mailed statement. "We're working to more accurately align the view-source: page with expected behavior."

In a phone interview, Hansen acknowledged that this bug isn't particularly serious because the only people who regularly view Web page source code are developers and because the Chrome installed base is still small.

"It's not like an earth-shattering bug," he said. "I just find it sort of weird when people talk about Chrome as super-secure. It's built with WebKit and WebKit is not necessarily secure."

WebKit is the open source browser layout engine used by Chrome and Apple's Safari Web browser. Microsoft's Internet Explorer uses a proprietary layout engine called Trident. Mozilla's Firefox uses a rendering engine called Gecko.

With regard to WebKit's security, Hansen said, "I don't think WebKit really has had enough eyeballs on it."

And he says Mozilla's Firefox has security problems that arise from the same lack of focused scrutiny by security professionals. "For the most part, it's just a bunch of random dudes who are contributing to it," he said.

Internet Explorer, he insists, is leaps and bounds more secure than the competition because so many more people are pounding on it.

Nevertheless, in the past three months Microsoft has issued three "browser-and-get-owned" security advisories regarding non-browser software components that have undermined the security of Internet Explorer.

While Microsoft's secure coding practices may lead to better security from the statistical perspective of bugs per lines of code -- and that's an issue about which there's ongoing debate -- Hansen isn't recommending Internet Explorer. "I'm not saying if you use Internet Explorer you're safe," he said. "There isn't a secure browser."

Though he says that friends of his in the security industry have confided that Firefox is full of bugs, he says he uses Firefox because "it's better for breaking into stuff."

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