Installing an antivirus software allows you to scan and remove viruses off your Mac. As of 2015, some antivirus software is available to download for free, but paid versions tend to provide more security features. After downloading the software, you must scan your Mac and any connected external hard drives for viruses. If viruses are detected, the software should provide a tool to remove the viruses.
Additionally, scan your Mac with a different program to get a second assessment. Even after removing viruses with one type of software, viruses might regenerate with portions being left behind in your Mac. Reformatting your Mac is another available option for removing viruses, but the process is much longer. Avoid viruses by steering clear of possible Facebook scams and not opening phishing emails.
A Flashback Trojan type of malware, commonly known as a Trojan horse, is similar to a virus and might be found on some Macs. The Trojan horse cannot infect other computers, but it might steal data or record keystrokes. In 2012, an estimated 600,000 Macs were reported as being infected with this type of malware. Using malware detection software allows users to remove the Trojan horse by scanning the Mac and rebooting it afterwards.