More than 30,000 WordPress blogs have been infected in a new wave of attacks from a cybercriminal gang which wants to distribute rogue antivirus software.

Security outfit Websense said that more than 200,000 infected pages that redirect users to websites displaying fake antivirus scans have been created. The latest compromises are part of a rogue antivirus distribution campaign that has been going on for months, the Websense researchers said.

Cybercriminals gangs have switched to drive-by download attacks that exploit vulnerabilities in outdated browser plug-ins to automatically download and install their rogue software. The large number of infected Web pages seen in this campaign is an indication that these scams still work. Vulnerable websites are a rich source of opportunity for cybercriminals. More than 85 percent of the compromised sites were located in the US, but their visitors were geographically dispersed.