Corporation has made a significant investment over the past few years
researching and combating malicious and potentially unwanted software,
and in developing technology to help customers mitigate the security
risk that it creates. As part of this investment, Microsoft created a
dedicated antimalware team that is responsible for researching
malicious software (or “malware”) and potentially unwanted software. In
addition, this team is responsible for the release and maintenance of
the Microsoft® Windows Malicious Software Removal Tool (MSRT) and
Windows Defender.

This report focuses on the first half of the 2006 calendar year
January to June) [H106] and expands upon a white paper Microsoft
released in June 2006 entitled MSRT: Progress Made, Lessons Learned
(http://go.microsoft.com/fwlink/?linkid=67998). Compared to the MSRT
paper, this report includes more recent results based on a
significantly expanded set of data sources. Using data derived from
several hundred million Windows users, this report provides an in-depth
perspective of trends in the malicious and potentially unwanted
software landscape.