A New Vector For Hackers -- Firefox Add-Ons

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Security

Makers of some of the most popular extensions, or "add-ons," for Mozilla's Firefox Web browser may have inadvertently introduced security holes that criminals could use to steal sensitive data from millions of users.

By design, each Firefox extension -- any of a number of free software applications that can be added to the popular open-source browser -- is hard-coded with a unique Internet address that will contact the creator's update server each time Firefox starts. This feature lets the Firefox browser determine whether a new version of the add-on is available.

Mozilla has always provided a free hosting service for open-source extensions at addons.mozilla.org. But many third-party makers opt to serve updates on their own, using servers that often transmit the updates via insecure protocols (think http:// instead of https://).

As a result, if an attacker were to hijack a public Wi-Fi hot spot at a coffeehouse or bookstore -- a fairly trivial attack given the myriad free, point-and-click hacking tools available today -- he could also intercept this update process and replace a Firefox add-on with a malicious one.

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