Summarize:

Download Malwarebytes for Mac, a free anti-malware app recommended by security experts. The application will download automatically. ” The entire file name should look like MBAM-Mac-1.2.5.dmg, though the number will vary based on the current software version.   ”  ” The app should open. If you see a message that says it can’t be opened because it wasn’t downloaded from the app store:  Open System Preferences. Select “Security & Privacy”. Click Open Anyway.  This will install the tool that removes any malware discovered by Malwarebytes. When the tool is finished installing, you’ll arrive at the main Malwarebytes Anti-Malware screen. The scan is fast, so don’t be alarmed if the results (or lack thereof) show up after only a few seconds. If the system has no malware, you will see a message that says no threats were found. If threats were found, a list will appear in a pop-up window. Unless otherwise noted, you should remove all threats found by the application.  Your Mac is now free of malware.
Open a web browser. Navigate to https://www.malwarebytes.com/mac-download/. Double-click the file that begins with “MBAM-Mac. Drag the Malwarebytes icon to the Applications folder. Click the “File” menu. Click “Eject Anti-Malware for Mac. Open the Applications folder. Double-click “Malwarebytes Anti-Malware. Click Open. Type your admin username and password. Click Install Helper. Click Scan. Evaluate the results. Place a checkmark next to each threat you want to remove. Click Remove Selected Items.