Not all malicious hackers make money by stealing it. 2005 saw large numbers of tech savvy criminals generating significant incomes by compromising computers so people are bombarded with pop-up ads or have their web browser hijacked so it takes them to sites they would not otherwise visit.
Behind these pop-up bombardments and browser hijackings are so-called adware and spyware programs. These can be contracted by visiting the wrong website which forces the installation of adware; by downloading applications such as file-sharing programs in which the adware lurks or by following a link in an e-mail.
Virus writers are starting to target online game players
Online security firm ScanSafe, which cleans up web traffic for customers, said the amount of spyware it had blocked was doubling every month since it started its monitoring program earlier in 2005.
It also said that the number of web-based attacks that try to install spyware and adware had grown by 165% in the last 12 months.
Spyware makers were working hard to stop their creations being found said Eldar Turvey, chief executive of ScanSafe.
"Spyware is becoming more stealthy," said Mr Turvey. Many viruses are designed to be disposable but spyware makers want their creations to persist.
Many spyware makers were disguising the data their programs send back by making it look like ordinary web browser traffic that easily slips through firewalls.
One final worrying trend seen in 2005 was the emergence of attacks aimed at security software.
Many makes of anti-virus, firewall and PC protection programs are seen as a weak link by hacker groups.
Many are trying to subvert the programs that are supposed to protect users and exploit weaknesses to give them access to users' machines.