Chrome apes IE8, adds clickjacking, XSS defenses

Google yesterday announced it has added several new security features to Chrome, including two that were first popularized by rival Microsoft in Internet Explorer 8 (IE8) last year.

The newest “stable” build of Chrome — Google's term for a production-quality edition — includes five security additions that target Web developers who want to build more secure sites, said Adam Barth, a software engineer on the Chrome team.

Of the five features, two are notable because they're already part of IE8, a browser many consider behind the times — and one that has trouble keeping up with competitors, such as Chrome and Mozilla's Firefox, which are upgraded more frequently.

Chrome now supports “X-Frame-Options,” a security feature that helps sites defend against “clickjacking” attacks, Barth announced.

Microsoft added an anti-clickjacking feature to IE8, although one of the security researchers who first reported the problem the year before, said IE's new feature would have “zero impact” on protecting users.

Clickjacking was first used in September 2008 by Robert Hansen, CTO of SecTheory LLC and Jeremiah Grossman, CTO of Whitehat Security, to describe browser-based attacks that tricked users into clicking on site buttons or Web forms. Such attacks hide malicious actions under the cover of a legitimate site, and theoretically can be used to empty online bank accounts, secretly turn on Web cameras or change a computer's security settings.

The other Chrome security feature inspired by IE8 is cross-site scripting protection. “In Google Chrome 4, we've added an experimental feature to help mitigate one form of XSS [cross-site scripting], reflective XSS,” Barth said. “The XSS filter checks whether a script that's about to run on a Web page is also present in the request that fetched that Web page. If the script is present in the request, that's a strong indication that the Web server might have been tricked into reflecting the script.”

Cross-site scripting attacks were prominent in 2008, less so last year, and are often used by identity thieves as part of a broader phishing campaign.

Barth acknowledged that the XSS filter now in Chrome resembles the one in IE8, as well as the NoScript add-on for Firefox. The difference, Barth argued, is that Chrome's filter comes courtesy of WebKit, the open-source browser rendering engine that is the foundation of Chrome as well as Apple's Safari. Because the XSS filter is integrated with the engine, said Barth, it “can catch scripts right before they are executed, making it easier to detect some tricky attack variations.”

Microsoft delivered the final version of IE8 in March 2009.

Google upgraded Chrome for Windows to version 4.0 last Monday. The new edition patched 13 security vulnerabilities, and added support for both bookmark synchronization and browser extensions.

Chrome can be downloaded for Windows XP, Vista and Windows 7 from the company's site.