Onde posso obter o cordbg.exe?
Você mesmo o constrói (ele é fornecido como um dos aplicativos de amostra fornecidos com o Microsoft .NET Framework SDK).
The Runtime Debugger helps tools vendors and application developers find and fix bugs in programs that target the .NET Framework common language runtime. This tool uses the runtime Debug API to provide debugging services.
The source code for Cordbg.exe is being shipped as a sample application.
Developers can examine the code to learn how to use the debugging services. Currently, you can only use Cordbg.exe to debug managed code; there is no support for debugging unmanaged code.
Fonte Depurador de tempo de execução (Cordbg.exe)