Question: suspicious malware pop-up on Safari- is it a scam?
Mac OS X 10.12.6 is infected with Viruses and other malicious applications. Viruses must be removed and system damage repaired.
It is necessary to run the Virus removal procedure immediately, please proceed.
**If you leave this site your Mac OS X Sierra will remain damaged and vulnerable**
MacBook Air (11-inch, Early 2014), macOS Sierra (10.12.4)