Update 5-1-2014: We can confirm Cisco customers have been targets of this attack. For the latest coverage information and additional details see our new post on the VRT blog.
The recent discovery of a new Internet Explorer zero-day exploit underlines how exposed web browsers are to vulnerabilities for which a patch is yet to be released. Cisco is aware of the issue and is releasing IPS signature 4256-0 and Snort signatures 30794, 30803 to detect the exploitation of this vulnerability. You can read more details from Cisco here.