Businesses have been warned to be alert to fraudsters posing as representatives of major web security vendors at the start of 2010's Get Safe Online week.
At the launch of the event, which is co-sponsored by the government, the Serious Organised Crime Agency (SOCA), Ofcom and supported by vendors including Trend Micro and Verisign, the organisers raised the alarm over the growing number of consumers and businesses falling victim to security scams.
Research carried out for GetSafeOnline.org suggested that a quarter of UK web users had been targeted by scammers, either through web pop ups that trick users into downloading malware on the pretext of securing the PC, or via cold calls from bogus security experts.
Victims are misled into thinking that their hardware has been compromised and typically charged around £30 to download a fake 'patch', with the ultimate goal being to secure credit card details or to take control of the victim's machine.
In recent cases SOCA claims it has seen gangs employing up to 400 people to run their operations and paying up to $150,000 a month to individual webmasters to unwittingly advertise their fake products.
GetSafeOnline.org managing director Tony Neate said: "Web users should ignore cold calls from companies offering free virus checks. Reputable IT providers do not approach customers in this way."
GrIDsure founder and CTO Stephen Howes said the initiative's attempt to raise awareness was commendable, but pressure had to be brought to bear by service providers and resellers too.
"Most computer users don't know or care what the latest iteration of the ZeuS banking Trojan is, or which antivirus software offers them the best protection," he said.
"So while user education of the risks is always important, I believe that the online service providers should put in place systems that are easy to use and secure enough to make it very difficult for a hacker to steal logon details even if they have infected the users' PC," Howes added.
The research also revealed that 34% of UK Internet users had been the victim of a virus attack, 22% had fallen prey to phishing scams, and 21% had had their identities stolen.