They infected computers that were used for false clicks on advertising.
Cyber security specialists of the company Icebrg discovered four malicious extensions for the browser Google Chrome, which users downloaded about 500 thousand times. This is written by ArsTechnica.
Experts told about programs under the names HTTP Request Header, Nyoogle, Stickies and Lite Bookmarks. All of them infected computers that were then used to click on sponsored links.
In addition, extensions could be used by cybercriminals to spy on users and owners of infected devices.
Google removed all four programs after a confidential message from Icebrg, the company said.