Celebrities are a bigger lure than sex when it comes to getting users to download adware or spyware, according to research by an antivirus vendor.

The common view that adult and pornography websites are the most prolific distributors of malware has been challenged by stats collected by McAfee SiteAdvisor. 

McAfee said that its research proved that adware and spyware distributors are abusing the affiliate marketing programmes of legitimate companies. 

"In addition, adware distributors use front companies and websites to reach unsuspecting users and intermediaries, meaning that legitimate sites are finding themselves tied to known spyware distributors," the report said.

These programs then install themselves on a user's machine, often as the trade-off for a piece of 'free' software, and are used to collect marketing data and distribute targeted advertising.

"The emergence of lucrative online affiliate-marketing business models, and the widespread ease with which adware and spyware can be spread, have made them prominent features in the threat landscape," said Jeff Green, senior vice president of product development at McAfee.

McAfee explained that the amount of adware and spyware is increasing at an exponential rate, and by August 2006 there were approximately 450 adware families with more than 4,000 variants.

"From 2003 to 2006, we have seen the number of adware families rise by more than 1,000 per cent," said Green.

He added that the lucrative nature of the adware business model made it a big draw, as witnessed by a recent criminal indictment alleging that Jeanson James Ancheta, a convicted bot-herder, received $150 (£81) for each of 1,000 infected computers.