During Blackhat DC, Microsoft released some updates to its secure development tools. Microsoft did some very nice work with these tools. While these tools are not necessarily limited to .Net, I highly recommend that .Net developers take a look at them.
The (at least to me) new tool is the Attack Surface Analyzer . It compares the state of your system before and after you install software to determine the impact your software has on the system, what resources it depends on and what changes it makes. It will also enumerate possible security issues. A Microsoft SDL blog article has more details .
BTW: if you are managing developers, and want to know more about threat modeling and common vulnerabilities: I will be teaching the 1 day software security awareness class in San Francisco on March 9th.
Johannes B. Ullrich, Ph.D.
SANS Technology Institute
(c) SANS Internet Storm Center. http://isc.sans.org Creative Commons Attribution-Noncommercial 3.0 United States License.