From bleepingcomputer.com
As users become more concerned about their privacy and being tracked online, they have begun to use ad blockers and script blockers to block JavaScript tracking scripts. A new method has been discovered that allows a site to track the mouse movements of their visitors by using only HTML and CSS, which can bypass tracking protection.
Most online tracking is done through JavaScript scripts loaded into web sites and advertisements. This allows advertisers and sites to track where you go on the web, how you use a site, or other online behavior.
These scripts can be blocked by using Ad Blockers, browser tracking protection such as Firefox’s Content Blocking, or blocking JavaScript altogether.