What does System Scan message mean?

An icon pops up in upper left of my Mac Pro screen "System Scan is recommended" and I question its reliability?

That would be adware. Download and run Malwarebytes. Malwarebytes was developed by one of our own colleagues here in ASC. It gets rave reviews and is about the most proven anti-malware software for Mac.

最后更新：2017-10-16 00:44:04