Microsoft confirmed on Tuesday that online attackers have seeded a group of Web sites with an exploit that uses a previously unknown flaw in Internet Explorer to compromise visitors' fully patched systems.
Researchers at security firms Sunbelt Software and Websense reported the attack to the software giant, which released an advisory the same day. The attack uses the same group of sites previously used by the WebAttacker Toolkit, making it appear that the attacks are related, said Websense in a posting to its research blog.
"Although we do not have evidence that the WebAttacker toolkit has been updated, there is a high level of probability that it has, as they have been on top of exploits in the past," Websense warned in the posting. "Currently there are thousands of sites on the web that use the WebAttacker Toolkit which may lead to high numbers of sites exploiting this newest unpatched vulnerability."
A number of zero-day attacks have plagued Microsoft this year, especially focusing on the company's Office productivity suite. Earlier this month, independent security researchers reported that online attackers had started taking advantage of a previously unknown flaw in Microsoft Word to compromise machines.
Posted by: Robert Lemos