Internet Explorer: zero-day exploit

There is exploit code for a zero-day Internet Explorer vulnerability circulating actively in the wild. This exploit, which has a Microsoft advisory, causes a heap overflow in the XML parser which can then be used for remote code execution.

The SANS Internet Storm Center has published a detailed blog talking about this exploit. Sophos has published Exp/Datbi-A to detect this code specifically, and we also have a knowledgebase article for this exploit.