Malware written using Microsoft's (MS's) .NET Framework operates differently from your standard compiled Portable Executable (PE). The framework, often pronounced \dot net," provides modern, functional, and easy-to-use assemblies for creating current-generation software. Once the C Sharp (C#), Visual Basic (VB.NET) or other .NET language is compiled, the result is MS Intermediate Language (MSIL). Upon being executed, the MSIL-based PE uses a just-in-time (JIT) compiler to generate native code, which is what we see run when .NET software/malware executes. Wonderfully for both the malware hobbyist and reverse engineering guru alike, MSIL PEs are easily decompiled back to source code. In this talk, SANS Instructor Ryan Chapman will provide an overview of the .NET framework, discuss malware families known to depend upon the framework, and provide analysis methodologies and tools for ripping these samples apart with ease.