A browser extension was leaking users' personal data.
A browser extension was leaking users' personal data.

A free web browser extension came at a cost: It leaked users' personal data, according to PCWorld.

The widely used extension, Web of Trust (WoT), uses crowdsourced data to alert users when a site is potentially deploying malware. But a report from Germany-based Norddeutscher Rundfunk (NDR) determined that the company behind the add-on, WOT Services, was selling users' browser histories without anonymizing the data, thus potentially exposing personal information. Additionally, the report said the company was not properly informing users of its data collection procedures.

After the news broke, Mozilla deleted Web of Trust from its Firefox browser marketplace. WOT Services then removed its add-on from the extension libraries of the other major browsers.

While the company claimed it anonymized browser histories it collected and then sold, the NDR reporters, from a small sample, were able to unmask details – including email and phone numbers – on more than 50 users.

WOT Services said it was revamping its add-on, but was unclear when it might reintroduce it.

Users are advised to manually uninstall the extension.