Scab.world sudden alerts you have encountered in your browser recently are related to distribution of many scary notifications through many popular browsers. The aim of such pop-ups is to infect your Mac system with a lot of other totally useless utilities, most likely fairly classified as adware, browser hijackers, fake system optimization tools and other potentially unwanted applications you definitely do not want. Furthermore, installing these programs which might be suggested by scab.world pop-ups typically harms your computer in general, both its hardware and software components.