Many Google Chrome and Microsoft Edge browser add-ons, including several prominent products, were found to be spying on users and communicating with a third-party server, in what appears to be a supply-chain attack with millions of victims.

The Geco extension has more than 800 reviews on the Chrome Web Store, 4.2 stars (out of 5), and "featured" placement. Microsoft's Edge Add-ons shows similarly glowing write-ups from its 1,000-plus users, and it looks like a perfectly safe extension.

According to researchers at Koi Security, the malicious extensions were part of a coordinated operation involving at least 18 known add-ons listed on the Chrome and

Researchers from Koi Security have detected 18 malicious Chrome and Edge extensions masquerading as benign productivity and entertainment tools

Users can use a shortcut parameter to limit the amount of cache Google Chrome uses. Unfortunately, there is no option within the program itself.