MBR Dump With .NET - Part 1

Greetings. Years ago I was messing around with Windows MBR (VXHeaven thread) and got stuck while trying to write a modified copy back to the disk. I'm calling this "Part 1" because I'm still stuck at this and plan to get back on my research.

Anyways, it will be a short post, just to share where I was at that time.

using System;
using System.Runtime.InteropServices;
using Microsoft.Win32.SafeHandles;
using System.IO;

namespace MBR
{
    class MainClass
    {

        [DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
        static extern uint SetFilePointer(
            [In] SafeFileHandle hFile,
            [In] int lDistanceToMove,
            [Out] out int lpDistanceToMoveHigh,
            [In] EMoveMethod dwMoveMethod);

        [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
        static extern SafeFileHandle CreateFile(string lpFileName, uint dwDesiredAccess,
            uint dwShareMode, IntPtr lpSecurityAttributes, uint dwCreationDisposition,
            uint dwFlagsAndAttributes, IntPtr hTemplateFile);

        [DllImport("kernel32", SetLastError = true)]
        internal extern static int ReadFile(SafeFileHandle handle, byte[] bytes,
            int numBytesToRead, out int numBytesRead, IntPtr overlapped_MustBeZero);


        public enum EMoveMethod : uint
        {
            Begin = 0,
            Current = 1,
            End = 2
        }

        public static void Main (string[] args)
        {
            Console.Title = "MBR Dumper";
            Console.WriteLine ("Dump MBR to raw.bin? (Y or N)");
            string ans = Console.ReadLine ();

            if (ans == "Y" || ans == "y") { 
                Console.WriteLine("\nDumping...");
                Dump ();
                Console.WriteLine("Done!");
                Console.ReadKey (true);
            } else {
                Environment.Exit (0);
            }

        }

        public static void Dump() {
            uint GENERIC_READ = 0x80000000;
            uint OPEN_EXISTING = 3;

            SafeFileHandle handleValue = CreateFile (@"\\.\PHYSICALDRIVE0", GENERIC_READ, 0, IntPtr.Zero, OPEN_EXISTING, 0, IntPtr.Zero);
            if (handleValue.IsInvalid) {
                Marshal.ThrowExceptionForHR (Marshal.GetHRForLastWin32Error ());
            }
            int offset = int.Parse ("0", System.Globalization.NumberStyles.HexNumber);
            int size = int.Parse ("200", System.Globalization.NumberStyles.HexNumber);
            byte[] buf = new byte[size];
            int read = 0;
            int moveToHigh;
            SetFilePointer (handleValue, offset, out moveToHigh, EMoveMethod.Begin);
            ReadFile (handleValue, buf, size, out read, IntPtr.Zero);
            FileStream myStream = File.OpenWrite ("raw.bin");
            myStream.Write (buf, 0, size);
            myStream.Flush ();
            myStream.Close ();
            handleValue.Close ();

        }
    }
}

That's it, MBR will be dumped to "raw.bin" in your current application directory. You can open it with a text editor or even better, a hex editor and modify as you wish. I will keep my work on this and if I ever find a way to write it back to the disk (tried several things already, no luck), I will post a Part 2.