Hi YoKenny,
This scheme is responsible for 20% of website infections mainly through clicking ads on commercial websites and social networks. As soon as visitors go to these infected pages, malware is being downloaded silently onto their computer without the user is aware of this. Next to that cybercrinminals also try to get users interested in free test versions of software. This is a trick to get to their personal data because victims will fill out a web form, so victims will pay hundreds of dollars for some fake worthless software. It is very hard to get to the cyber criminals, because they use botnets where senders of malcode ads may vary all the time, according to GData's Klier.
Criminals also make use of media hypes, as the one about conficker, so they built fake sites by buying Google ads that will come up high in the search rankings so their criminal actions will be "fruit"ful,
polonus
