Does / is DNN abiding to any sort of securities standard such as OWASP? http://www.owasp.org/ 

If any security standard is upheld, what standard is it?

I need this information to defend the use of DNN in a project, and I just found out about it... Any information would be greatly appreciated.

I don't know how old Cathal's analysis is but keep in mind that DNN 4.x running under the medium trust model (with ASP.Net 2.0) makes a leap in security that previous versions did not achieve.  If security is a big concern for your project you should read on the setup of DNN under the medium trust model (versus the typical full trust).  Also, 4.4.1 and its new philosophy of installing only a minimum of the modules for performance reasons reduces the attack surface considerably.  You also have all the source code for analysis if you wish to do that.

In any case, ask the management what the alternatives are, write your own application infrastructure from scratch?  Get a commercial product that is going to be expensive and not as thoroughly tested? (notice that DNN has thousands of installations)  Also keep in mind that the DNN security is going to be as good as the server it is running on, meaning that best security practices for the management of Windows server, IIS, and SQL Server must be followed.  One more thing, recommend to use Window Server 2003.

The last thing for you to discuss is that even though DNN is open source, it is now backed by a formally organized corporation that has close ties to Microsoft (for technical development reasons).

Carlos