Malware/Adware

Read this excellent post about keeping your mac secure:

https://discussions.apple.com/docs/DOC-8841

In case you are concerned about a possible infection, you may run MalwareBytes, a reputable program by a respected member of the mac security community.

Never install any “antivirus”, “cleaner” or “optimizer”. They are designed to separate you from your money, not to protect your mac. Many of those programs should be considered malware themselves.

There are no known Windows-like Viruses in the wild that self replicate and affect macOS, because of the underling UNIX  Foundation and Permission Limitation. 

The Only thing this Antivirus software is protecting is the Bank Account of the Developers and for zero return to the User aside from the problems this software creates.

The The Built in Security  is all that is required to protect the computer.

Should “ Certain & Specific Software “ referenced from above be installed - it will negatively impact macOS. It is suggested, to download directly from a respected ASC Contributor, the application Malwarebytes for Mac. 

It is free or paid for added features. 

Run the Application and it should remove the malware / adware. Once done, restart computer and test.