I periodically clean my browser history, but after a while website entries begin to appear in it that I’ve never actually been to.
Exactly how a virus does this depends on its type, but can include propagation over removable media such as USB drives, networks, or network-based activities such as user downloads.
Foistware is additional software “foisted” on an unsuspecting user when some other software is installed.
The most common example of foistware might be additional toolbars and search add-ons that often accompany free software downloads.
Foistware may, or may not, include an option to be installed, but often installs without asking. Foistware” – the software that often appears on your system unexpectedly after installing something else. It’s possible your browser may simply be doing a good job protecting you.
Spyware often works by forcing your browser to go to places you would never go.
Foistware in particular often adds toolbars and other software to your system that intercepts what you’re doing and just rudely takes over, sending you to bogus search sites or worse.