Cybercriminals are stepping up their efforts to exploit vulnerabilities in web browsers to spread malware using drive-by download techniques.
Research by Google's anti-malware team on three million unique URLs on more than 180,000 websites automatically installed malware onto vulnerable PCs.
Hackers are increasingly trying to trick search sites into pointing surfers onto maliciously constructed sites. More than one per cent of all search results contain at least one result that points to malicious content, Google reports, adding that incidents of such attacks has grown steadily over recent months and continues to rise.
Google's team also reports that two per cent of malicious websites are delivering malware via tainted banner ads. Israeli security firm Finjan has also observed a rise in the tactic over recent months, noting that many malicious ads are served from legitimate websites.
A security report from IBM's X-Force division said cybercriminals are "stealing the identities and controlling the computers of consumers at a rate never before seen on the internet".
A complex underground economy has developed in services designed to make exploits more potent, involving tools to camouflage attacks on browsers.
"In 2006, only a small percentage of attackers employed camouflaging techniques, but this number soared to 80 per cent during the first half of 2007, and reached nearly 100 per cent by the end of the year. The X-Force believes the criminal element will contribute to a proliferation of attacks in 2008," IBM's security division said.
Miscreants are stealing online credentials from compromised machines or using them as a resource to send spam or mount hacking attacks, it adds. ®