A massive search-hijacking campaign involving 319 Chrome extensions with a combined 13.4 million reported installations redirected users’ searches through tracking servers to generate advertising revenue from Bing and Yahoo.

A new report by Socket’s John Tuckner expands on the researcher’s April 2025 discovery of 57 Chrome extensions with 6 million users, adding 264 newly identified add-ons with another 8.7 million users.

“These extensions were created by a handful of organized operators all working from the same idea: quietly take over the browser’s default search engine, route every query through a suspicious proxy server, and collect partner referral payments from Yahoo or Bing under a syndication partner ID,” explained Tuckner.