Security researcher Sam Jadali found out that browser extensions on Chrome and Firefox have stolen data not only from users but also from well-known companies such as Tesla and Apple.

Dubbed "DataSpii," the massive leak has been reported to affect millions.

Malicious Browser Extensions

The browser add-ons that have been discovered to be collecting and exposing private data are as follows:

• Hover Zoom

• SpeakIt!

• SuperZoom

• SaveFrom.net Helper

• FairShare Unlock

• PanelMeasurement

• Branded Surveys

• Panel Community Surveys

SuperZoom and FairShare Unlock are on Chrome and Firefox, while SaveFrom.net Helper is only on the latter. The rest are only on Google's browser.

In particular, SpeakIt! and FairShare Unlock have more than 1 million users, and others have hundred thousands. Meanwhile, at least two only had a small user base, one of which only had one user.

Some of the browser extensions listed above used certain measures to avoid getting detected. While others began harvesting info immediately, others waited 24 days after being installed before tracking data so that users wouldn't notice there was something suspicious. After gathering data, the perpetrators would sell it.

Jadali drew up a diagram that explains how the process works. The full detailed report of DataSpii is available on his website.

The security researcher has already notified Google and Mozilla about the leak. As a solution, the extensions have been disabled and removed from their catalogs, but despite that, they could still gather data. The best way to stop them on their tracks at the moment is to uninstall them.

Jadali has also informed the affected companies, who have substantiated his findings.

To reiterate, uninstall the eight browser extensions mentioned above as soon as possible, and just to be safer in the future, be wary of add-ons regardless of where they come from. Just because they're on Chrome's or Firefox's store doesn't automatically mean they're completely safe to use.