http://lotyong.googlepages.com/CsharpAsmClassLibrary.htm

using System;

using System.Collections.Generic;

using System.Text;

using System.Runtime.InteropServices;

namespace AsmClassLibrary
{

    public class AsmClass
    {
        #region API
        [DllImport("kernel32.dll", EntryPoint = "CloseHandle")]
        public static extern int CloseHandle(int hObject);

        [DllImport("kernel32.dll")]
        public static extern Int32 WriteProcessMemory(

            IntPtr hProcess,

            IntPtr lpBaseAddress,

            [In, Out] byte[] buffer,

            int size,

            out IntPtr lpNumberOfBytesWritten);

        [DllImport("kernel32.dll")]
        public static extern Int32 WriteProcessMemory(

            int hProcess,

            int lpBaseAddress,

            byte[] buffer,

            int size,

            int lpNumberOfBytesWritten);

        [DllImport("kernel32", EntryPoint = "CreateRemoteThread")]
        public static extern int CreateRemoteThread(

            int hProcess,

            int lpThreadAttributes,

            int dwStackSize,

            int lpStartAddress,

            int lpParameter,

            int dwCreationFlags,

            ref int lpThreadId

            );

        [DllImport("Kernel32.dll")]
        public static extern System.Int32 VirtualAllocEx(

            System.IntPtr hProcess,

            System.Int32 lpAddress,

            System.Int32 dwSize,

            System.Int16 flAllocationType,

            System.Int16 flProtect

            );

        [DllImport("Kernel32.dll")]
        public static extern System.Int32 VirtualAllocEx(

            int hProcess,

            int lpAddress,

            int dwSize,

            int flAllocationType,

            int flProtect

            );

        [DllImport("Kernel32.dll")]
        public static extern System.Int32 VirtualFreeEx(

            int hProcess,

            int lpAddress,

            int dwSize,

            int flAllocationType

            );

        /// <summary>
        /// 启动API
        /// </summary>
        /// <param name="dwDesiredAccess"></param>
        /// <param name="bInheritHandle"></param>
        /// <param name="dwProcessId"></param>
        /// <returns></returns>
        [DllImport("kernel32.dll", EntryPoint = "OpenProcess")]
        public static extern int OpenProcess(

        int dwDesiredAccess,

        int bInheritHandle,

        int dwProcessId

        );
        #endregion

        private const int PAGE_EXECUTE_READWRITE = 0x4;

        private const int MEM_COMMIT = 4096;

        private const int MEM_RELEASE = 0x8000;

        private const int MEM_DECOMMIT = 0x4000;

        private const int PROCESS_ALL_ACCESS = 0x1F0FFF;

        private const int PROCESS_CREATE_THREAD = 0x2;

        private const int PROCESS_VM_OPERATION = 0x8;

        private const int PROCESS_VM_WRITE = 0x20;

        #region Asmcode
        private string _asmcode = "";
        public string AsmCode
        {
            get { return _asmcode; }
            set { _asmcode = value; }
        }
        #endregion

        private string hex(int address)
        {

            string str = address.ToString("X");

            return str;

        }

        public string intTohex(int value, int num)
        {

            string str1;

            string str2 = "";

            str1 = "0000000" + this.hex(value);

            str1 = str1.Substring(str1.Length - num, num);

            for (int i = 0; i < str1.Length / 2; i++)
            {

                str2 = str2 + str1.Substring(str1.Length - 2 - 2 * i, 2);

            }

            return str2;

        }

        public void SUB_ESP(int addre)
        {

            if ((addre <= 127) && (addre >= -128))
            {

                this.AsmCode = this.AsmCode + "83EC" + intTohex(addre, 2);

            }

            else
            {

                this.AsmCode = this.AsmCode + "81EC" + intTohex(addre, 8);

            }

        }

        public void Nop()
        {

            this.AsmCode = this.AsmCode + "90";

        }

        public void RetA(int addre)
        {

            this.AsmCode = this.AsmCode + intTohex(addre, 4);

        }

        public void IN_AL_DX()
        {

            this.AsmCode = this.AsmCode + "EC";

        }

        public void TEST_EAX_EAX()
        {

            this.AsmCode = this.AsmCode + "85C0";

        }

        public void Leave()
        {

            this.AsmCode = this.AsmCode + "C9";

        }

        public void Pushad()
        {

            this.AsmCode = this.AsmCode + "60";

        }

        public void Popad()
        {

            this.AsmCode = this.AsmCode + "61";

        }

        public void Ret()
        {

            this.AsmCode = this.AsmCode + "C3";

        }