Web users who browse the infected sites will unknowingly load a file that automatically attempts to serve up a concoction of eight different exploits designed to gain access to their computers and install information-stealing malware, Websense says in its report.
The mass attack appears to be from the same group of individuals who launched a similar "iFrame" attack a few weeks ago, which compromised thousands of Internet domains, including U.S. news and travel sites.
"The attackers have now switched over to a new domain as their hub for hosting the malicious payload in this attack," Websense says. "We have no doubt that the two attacks are related."
In the space of just a few hours yesterday, Websense said it saw the number of compromised sites increase by a factor of ten.
Tim Wilson, Site Editor, Dark Reading