Eighty-five percent of all malware is web-based, and some 30,000 websites are newly infected with malicious code each day, according to Sophos' "Security Threat Report 2012."
The study (PDF), which polled 4,300 security professionals, found that while threats such as rogue anti-virus are dropping, there is an increase in drive-by downloads, by which users are infected with malware simply by visiting legitimate sites that have become compromised.
"People still aren't protecting their web gateways like they are their email gateways," Beth Jones, senior threat researcher at SophosLabs, told SCMagazine.com on Wednesday.
In many cases, an automated, commercially available exploit pack known as BlackHole is to blame, according to the report. Compounding the problem is that the BlackHole code is difficult to detect and is constantly updated to take advantage of newer vulnerabilities, which aren't as likely to be patched.
"BlackHole mainly spreads malware through compromised websites that redirect to an exploit site, although we've also seen cybercriminals use spam to redirect users to these sites," the report said. "This year we've seen
numerous waves of attacks against thousands of legitimate sites."
Web malware also is propagating through online advertisements and on social networking sites such as Facebook, Jones said.
Her top recommendation for deterrence is patching. But many enterprises are lacking on this front, as is evident by how prevalent the Conficker worm remains, despite it being patched nearly three years ago. Jones said 15 percent of infection attempts on Sophos customers are related to the pesky worm."It wasn't just an isolated incident," she said. "Conficker spread so fast. You get one machine infected with it and suddenly you have a very large problem."