There has been a lot of discussions in different blogs on the attacks on IIS servers. Microsoft Security Response Center has publised a post on it: Questions about Web Server Attacks
About the author
Roger Halbheer is an Executive Security Advisor at Microsoft in EMEA acting as a trusted advisor to CxO. Before that he was a Managing Director at Accenture's Financial Services. Before joining Accenture, he was the Chief Security Officer of Swisscom (Switzerland's largest telecom provider) and the global Chief Security Advisor for Microsoft.