IObit Malware Fighter Pro is on GOTD today, and this post is inspired by a [seemingly popular] comment. As far as IObit Malware Fighter Pro itself goes, if you like it you like it, no harm done. But where it uses the "Bitdefender antivirus engine", and normally costs $19.95, that's basically what I've paid for the full BitDefender Total Security suite for the last several years. Unfortunately IObit doesn't show up at av-test[.]org, which rates all the major players, so IObit's customers are paying the same amount for increased risk. [I've managed to find the top rated McAfee software for 1/2 that, while Defender, which comes with Win10, is top rated as well.]
Anyway, to the comment, it was talking about just running Anti Virus scans, rather than having the software running continuously. There are several apps, often free, offered by many security software companies for doing just that. Originating in root kits, the idea is that malware can change Windows so that certain files or file types are completely invisible. If the malware has not penetrated the BIOS, those hidden malware files should be visible before Windows starts, so sometimes this software requires a restart, while some will run the software after connecting the hard disk to another PC. Kaspersky's free TDSSKiller detects root kits while Windows is running.
OK, but what about other kinds or types of malware? Anti Virus scans aren't that much use... krebsonsecurity[.]com/2014/05/antivirus-is-dead-long-live-antivirus/
In fact, they can be worse than not having any protection at all. Malware developers know about AV software, and try to bypass it, turn it off, &/or co-opt it to do their mischief. Because of that AV software developers create deep roots in Windows, making things even more dangerous if/when it is co-opted by malware. Security software companies also keep tabs on the Virus Total web site & database. It allows posting and sharing new malware signatures that are used to ID threats. Because most anyone can contribute, some of the stuff that's uploaded is just wrong. Because security software is a competitive biz, sometimes it's allegedly purposely wrong.
The real protection you get from security software comes from monitoring what's going on when Windows is running. Ideally software is caught & stopped before it has a chance to do something naughty.
That said, the issue is moot if you're running Win10, because Defender is included. It'll step into the background if you install 3rd party security software, but step right back if you neglect updating it or remove it. It's been several versions since I tested it, but even if you succeed in turning Defender off, a separate sort of fail-safe version of the software would run instead.
SO, scanning for viruses in itself isn't evil, & may in some cases actually do some good, but don't go beating yourself up if you ignore your security software when it suggests running a scan.