In this mini series, I will discuss the microsoft .net framework security model. I recommend the following readings as introduction material to understand .net security model.
.net IL using ildasm and ilasm
Part 1 - Learn to break a .NET Assembly:http://www.codeproject.com/dotnet/NeCoder01.asp
Part 2 - Learn to protect your .NET assemblies from being tampered:http://www.codeproject.com/dotnet/NeCoder02.asp
Part 3 - Learn to break Strong Name .NET Assemblies:http://www.codeproject.com/dotnet/NeCoder03.asp
Understanding, programming and debugging IL .net application:
Part 1 Introduction
Part 2 A short description and .NET application
Part 3 Debugging
Tools (It can be said, a hacker is as good as his tools)
ildasm and ilasm (decompiler and compiler of intermediate language)
LORD PE (examine and modify PE header)
WINHEX (examine and modify binary file in hex mode)
REGEDIT (studying protection scheme used by certain softwares)
Now, there are 2 ways to actually patch a .net binary file, the first way is to directly patch the binary file with a hex editor; the second way is to decompile/modify/compile .net intermediate language (IL). Both approaches works equally well and the details of both methods are discussed in the URL links I provided.
Discusses the method used in this article
Has a section of .NET header in figure 10.
Details on how to crack .net protection.
For the old schools.