The number of malware-serving websites has rocketed 600 percent over the past year, according to researchers.
Security firm WebSense said that attackers are increasingly looking to construct websites which contain automated attack code. While some pages are deliberately built to serve malware, WebSense estimates that as many as 85 percent are otherwise legitimate pages which have been compromised.
"These attacks were staged predominantly on legitimate sites and challenge traditional approaches to security and trust," explained Websense Security Labs vice president Charles Renert.
"The timed, targeted nature of these advanced threats indicates a new breed of sophisticated attacker who is intent on compromising increasingly higher-yield targets."
The growth in attack sites coincides with a rise in the use of automated exploit kits. The attack kits, which can cost hundreds of dollars, are able to inject code into a web page which automatically attempts to perform exploits on a number of common vulnerabilities.
More sophisticated packages can also screen for operating systems, browser type and version number.
In addition to the rise in malicious pages, researchers believe that Trojan downloaders are becoming more efficient in infecting users. WebSense reported that half of the downloaded malware it observed will download and execute additional malicious applications within 60 seconds of installation.
Websites containing malware were most likely to target audiences in the US, Russia and China. Those three countries were also the most likely to house the command servers behind the malware, although China was a more common location than the US.
Websense also logged increases in social networking and mobile malware. Researchers noted that 32 percent of malicious links on social networks were now using URL-shortening tools to obfuscate themselves, making detection by end-users more difficult.
For mobile malware, the 'Trojan' approach is growing in popularity. Websense found that one in every 10 malicious applications attempted to download and install additional applications, a common technique in desktop malware.