Google Tightens Rules for Chrome Extensions
2.10.2018 securityweek Privacy

Google this week announced a series of policy changes and updates to improve the overall security of Chrome extensions.

There are currently more than 180,000 extensions available in the Chrome Web Store, and nearly half of Chrome desktop users actively use extensions, which makes the security of these components critical to the user browser experience.

Over the past couple of years, there have been numerous incidents where Chrome extensions were abused for traffic hijacking, click fraud, or adware distribution. After removing inline installation of extensions earlier this year, Google is changing the rules again to better protect Chrome users.

Starting with Chrome 70, users will be able to either restrict extension host access to a custom list of sites, or to configure them to require a click to gain access to the current page, James Wagner, Chrome Extensions Product Manager, reveals.

Host permissions, Wagner notes, allow extensions to automatically read and change data on websites, thus being prone to misuse, either malicious or unintentional. Thus, the search giant has decided to improve user transparency and control over when extensions can access site data and developers are advised to make the necessary changes to their apps as soon as possible.

The review process will tighten for extensions that request powerful permissions, as well as for those that use remotely hosted code, which will be subject to ongoing monitoring, Wagner notes. Developers should ensure their extension’s permissions is as narrowly-scoped as possible and that all the code is included directly in the extension package, to minimize review time.

Starting October 1, extensions with obfuscated code are no longer allowed in the Chrome Web Store, regardless of whether the obfuscation is applied to code within the package or to external code or resources. Existing extensions with obfuscated code will be removed in early January, provided that they don’t receive updates to become compliant.

“Today over 70% of malicious and policy violating extensions that we block from Chrome Web Store contain obfuscated code. At the same time, because obfuscation is mainly used to conceal code functionality, it adds a great deal of complexity to our review process. This is no longer acceptable given the aforementioned review process changes,” Wagner points out.

Extension developers are still allowed to use minification, which not only speeds up code execution by reducing size, but also makes extensions more straightforward to review. Techniques that are allowed include removal of whitespace, newlines, code comments, and block delimiters; shortening of variable and function names; and collapsing the number of JavaScript files.

Starting in 2019, Google will also require all Chrome Web Store developer accounts to enroll in 2-Step Verification. This should add extra protection to prevent incidents where attackers attempt to steal popular extensions by hijacking the developer account.

“For even stronger account security, consider the Advanced Protection Program. Advanced protection offers the same level of security that Google relies on for its own employees, requiring a physical security key to provide the strongest defense against phishing attacks,” Wagner says.

Next year, Google also plans on introducing the next extensions manifest version, which should improve security, privacy, and performance. It will bring more narrowly-scoped and declarative APIs, easier mechanisms for users to control the permissions granted to extensions, and alignment with new web capabilities, such as supporting Service Workers as a new type of background process.

“We recognize that some of the changes announced today may require effort in the future, depending on your extension. But we believe the collective result will be worth that effort for all users, developers, and for the long term health of the Chrome extensions ecosystem. We’re committed to working with you to transition through these changes and are very interested in your feedback,” Wagner concludes.