Twenty million users of Google Chrome were fooled into installing fake ad-blocker extensions. Researchers at AdGuard made the discovery.

Here’s how the crooks do it. They take a legitimate ad-blocking program and add some of their own code on top of it. They name it something similar to the original program. These extensions come up in the search results when you look for ad blockers in the Chrome store.

ad-blocker-fake.jpg

These extensions contain malware that sends information back to the scammers about what sites you visit and are capable of taking control of your browser to direct it wherever they want.

Here’s a list of the affected extensions. Three of them are adblockers. The other two are programs the security researchers discovered work in the same way.

•AdRemover for Google Chrome™
•uBlock Plus
•Adblock Pro
•HD for YouTube™
•Webutation

AdGuard reported this discovery to Google and the extensions have since been removed from the store.

You can click here to read a detailed description of how AdGuard determined the extensions were malicious.