Unable to inject dll into process?

Question

C++ / C#

Hello.
There is such a code for injecting a dll into a process

HANDLE h_process = OpenProcess(PROCESS_ALL_ACCESS, FALSE, PID);

  char fullDLLPath[_MAX_PATH];
  GetFullPathNameA(file_name.c_str(), _MAX_PATH, fullDLLPath, NULL);

  LPVOID DLLPath_addr = VirtualAllocEx(h_process, NULL, _MAX_PATH,
    MEM_COMMIT | MEM_RESERVE, PAGE_READWRITE);
  WriteProcessMemory(h_process, DLLPath_addr, fullDLLPath,
    strlen(fullDLLPath), NULL);

  LPVOID LoadLib_addr = GetProcAddress(GetModuleHandleA("Kernel32"),
    "LoadLibraryA");

  HANDLE h_rThread = CreateRemoteThread(h_process, NULL, 0,(LPTHREAD_START_ROUTINE)LoadLib_addr, DLLPath_addr, 0, NULL);

  WaitForSingleObject(h_rThread, INFINITE);

  DWORD exit_code;
  GetExitCodeThread(h_rThread, &exit_code);                                         
  CloseHandle(h_rThread);
  VirtualFreeEx(h_process, DLLPath_addr, 0, MEM_RELEASE);
  CloseHandle(h_process);

  return (HANDLE)exit_code;

But when I call it like this:

di.inject_DLL("module.dll", di.GetPID("winhex.exe"));

PS This is class. Here is another GetPID function

HANDLE hSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, NULL);
  PROCESSENTRY32 pe32;
  pe32.dwSize = sizeof(PROCESSENTRY32);
  if (hSnap) {
    if (Process32First(hSnap, &pe32)) {
      if (strcmp(pe32.szExeFile, processname.c_str()) == 0) {
        return pe32.th32ProcessID;
      }
    }

    while (Process32Next(hSnap, &pe32)) {
      if (strcmp(pe32.szExeFile, processname.c_str()) == 0) {
        return pe32.th32ProcessID;
      }
    }

    CloseHandle(hSnap);
    return 0;
  }
  else {
    return 0;
  }

So.
After the call, nothing happens.
I do not inject into a system process.
I tried to inject through Process Hacker and everything worked.
What could be the problem?

Answer 1

Laughed myself. The decision was easy enough.
I called the function incorrectly.
Called:

di.inject_DLL("winhex.exe", di.GetPID("winhex.exe"));

Need:

di.inject_DLL("module.dll", di.GetPID("winhex.exe"));

Thank you all for your help.

Answer 2

Try like this:

LPVOID LoadLib_addr = GetProcAddress(GetModuleHandleA("kernel32.dll"), "LoadLibraryA");

And check if the DLL was loaded successfully:

if (h_rThread)
{
  <код>
}

Answer 3

Of course, I understand that laziness, but you always need to write error handling, then it would be obvious where the problem is. I have 2 options why it might not work:
1. The bitness of your application is not the same as that of the attacked process.
2. The location of kernel32 in the attacked process is different from the location in yours.