Enhances protection by checking against an always up-to-date cloud database of antivirus signatures. One annoyance of free antivirus software is that each program displays ads for the full, paid version of the product. The most important thing to consider when you search for the right security software is its ability to defend your computer against attacks. Trend Micro Internet file security software Security includes all the functionality of HouseCall, plus automatic virus updates personal firewall, spyware detection and removal, spam blocking, protection against identity theft, and Wi-Fi network protection. CM Security had some viral success back when it was one of only a few free antivirus Android apps and was, at the time, the best free option available.