Photos: How does spyware get on your PC?

Some methods of installing spyware on a PC are obvious to the more tech-savvy user. A pop-up which openly asks a user if they want to install an application may seem crude but if it tells a user they need this tool to access a website they may be inclined to click.

The use of an install window that users will have seen when installing applications they do want may also create an impression of legitimacy.

Often such windows will be persistent, said Chien, popping up repeatedly and preventing the user from navigating away. They will keep popping up until the user caves in or shuts down their browser via their task bar (ctrl + alt + del).

Media downloads can also be a source of spyware. Chien said he illegally downloaded episodes of Family Guy over BitTorrent "purely for research purposes" and found the files he received contained spyware application 180 Search Assistant, now called Zango.