Message from mac while using safari
your system is infected with 3 viruses immediate removal required!!!
Question marked as
Top-ranking reply
Adware/Malware. There isn't a way an outside source can tell if your system has viruses.
You may have adware/malware installed. Try downloading this program which was written by Thomas R, a long time poster. The program will search for malware/adware. The program will do the work for you which makes it easy. It may be necessary to run more than one scan. After running the scans, restart the computer.
Malwarebytes Anti-Malware for Mac 10.10 and later