Sometimes when I go to visit my parents, they ask me to fix their Macbook because something is wrong with Safari. The find that there is an extension installed and that it has set the home page in the browser. Unfortunately I don’t remember the name of the last one but I think it was “Smart Search” or “Safe Search” or something like that.
I know how to uninstall an extension, but I’m wondering how it gets installed in the first place. I think my parents know enough about computers to not download and install random programs of the internet so I suspect they are getting tricked into clicking something in a web page. But, is that possible? Can a website install an extension on the sly like that? It’s never happened to me.
They're running macOS High Sierra 10.13.5, Safari 11.1.1.