newstoday malware

A piece of malware has invaded my system. A message pops up saying my computer, email, cloud, or some other app is infected. Clicking leads to a website that wants me to download some purportedly scanning app which, of course, I do not do. Soon after the message appears, it disappears. From Activity Monitor, this appears to be some code labeled "newstoday." Also "newsd". I suspect, but cannot verify, that it is being launched by Safari, as it does not seem to appear when Safari is not active. I have run both malware bytes and CleanMyMacX, but neither detects it. Does anyone know how I can get rid of it?