Sophos attributes the increase to the business model used by virus writers.

The goal for virus writers is financial gain through long-term infection, which is why spyware usage has been so prevalent.

The global report, which was released today, found spyware rose to 66.4 percent of all malware threats in November this year.

In January, only 54.2 percent of all threats included a spyware payload and the year to date has shown a 48 percent increase in malware compared to 2004.

Sophos head of technology, Paul Ducklin, said virus writers are decreasingly writing viruses just for the sake of it and are instead turning to malicious code with a specific purpose, hence spyware.