Malicious keyloggers can identify every keystroke that is entered and can exploit that information.
Visiting harmful websites can also cause this if there is no active protection in place (like an updated antivirus application).
KeyScrambler is a very useful and free Windows utility that will encrypt each and every keystroke that is entered in all the browsers and thereby defeat the purpose of keyloggers. Download it from here.
The personal edition which is free encrypts keystrokes in all major browsers while the premium edition in addition to that covers 3rd party applications as well.
As it integrates with the kernel, a system reboot is necessary after installation for it to become active.
After installation and a reboot, whenever anything is typed in browser window , an encryption status bar on top of browser window will be visible indicating that real time encryption for entered keystrokes is in progress.
This works for login forms too.
The settings for KeyScrambler can be changed as well. Right click on it’s system tray icon and choose Options. Also, KeyScrambler can be turned on or off from here if needed.
Other options include changing the shortcut key for turning it on/off(default being Ctrl+Shift+K), the overlay of the encryption status bar and whether it will start up along with Windows.
This is a very useful utility that can provide a great deal of security online even if conventional antivirus utilities may or may not detect presence of malicious keyloggers. All of this without slowing down Windows or online activities.
Do give it try.