When in doubt, check the digital signature and scan the file with multiple engines. As with any executable, awareness and verification are your best defenses. This article is for informational purposes. Always refer to official F-Secure/WithSecure support channels for troubleshooting specific to your version and operating system.

In fact, the real fsmainui.exe is designed to protect your computer from malware. However, virus creators sometimes name their malicious files after legitimate processes to hide in plain sight.

If you do not use F-Secure, uninstall the program properly, and the file will disappear. If the file appears outside the F-Secure folder, scan it immediately.

Here is a quick checklist to verify the authenticity of your fsmainui.exe :