InjectDll.cs

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Drawing;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Inject_Dll
{
    public partial class Frm_Main : Form
    {
        public Frm_Main()
        {
            InitializeComponent();
        }

        [DllImport("kernel32.dll")]
        public static extern IntPtr OpenProcess(int dwDesiredAccess, bool bInheritHandle, int dwProcessId);

        [DllImport("kernel32.dll", CharSet = CharSet.Auto)]
        public static extern IntPtr GetModuleHandle(string lpModuleName);

        [DllImport("kernel32", CharSet = CharSet.Ansi, ExactSpelling = true, SetLastError = true)]
        static extern IntPtr GetProcAddress(IntPtr hModule, string procName);

        [DllImport("kernel32.dll", SetLastError = true, ExactSpelling = true)]
        static extern IntPtr VirtualAllocEx(IntPtr hProcess, IntPtr lpAddress,
            uint dwSize, uint flAllocationType, uint flProtect);

        [DllImport("kernel32.dll", SetLastError = true)]
        static extern bool WriteProcessMemory(IntPtr hProcess, IntPtr lpBaseAddress, byte[] lpBuffer, uint nSize, out UIntPtr lpNumberOfBytesWritten);

        [DllImport("kernel32.dll")]
        static extern IntPtr CreateRemoteThread(IntPtr hProcess,
            IntPtr lpThreadAttributes, uint dwStackSize, IntPtr lpStartAddress, IntPtr lpParameter, uint dwCreationFlags, IntPtr lpThreadId);

        const int PROCESS_CREATE_THREAD = 0x0002;
        const int PROCESS_QUERY_INFORMATION = 0x0400;
        const int PROCESS_VM_OPERATION = 0x0008;
        const int PROCESS_VM_WRITE = 0x0020;
        const int PROCESS_VM_READ = 0x0010;

        const uint MEM_COMMIT = 0x00001000;
        const uint MEM_RESERVE = 0x00002000;
        const uint PAGE_READWRITE = 4;


        private void Frm_Main_Load(object sender, EventArgs e)
        {

        }

        private void btn_ınject_Click(object sender, EventArgs e)
        {
            Process targetProcess = Process.GetProcessesByName(tb_pname.Text)[0];

            IntPtr procHandle = OpenProcess(PROCESS_CREATE_THREAD | PROCESS_QUERY_INFORMATION | PROCESS_VM_OPERATION | PROCESS_VM_WRITE | PROCESS_VM_READ, false, targetProcess.Id);

            IntPtr loadLibraryAddr = GetProcAddress(GetModuleHandle("kernel32.dll"), "LoadLibraryA");

            string dllName = tb_path.Text;

            IntPtr allocMemAddress = VirtualAllocEx(procHandle, IntPtr.Zero, (uint)((dllName.Length + 1) * Marshal.SizeOf(typeof(char))), MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);

            UIntPtr bytesWritten;
            WriteProcessMemory(procHandle, allocMemAddress, Encoding.Default.GetBytes(dllName), (uint)((dllName.Length + 1) * Marshal.SizeOf(typeof(char))), out bytesWritten);

            CreateRemoteThread(procHandle, IntPtr.Zero, 0, loadLibraryAddr, allocMemAddress, 0, IntPtr.Zero);

        }
    }
}