Windows C++ / Thread Execution Hijacking

Code

#include <Windows.h>
#include <TlHelp32.h>

int main()
{
    // Create a snapshot of all running threads
    HANDLE hSnapshot = CreateToolhelp32Snapshot(TH32CS_SNAPTHREAD, 0);

    if (hSnapshot != INVALID_HANDLE_VALUE)
    {
        THREADENTRY32 te32;
        te32.dwSize = sizeof(THREADENTRY32);

        // Enumerate all running threads
        if (Thread32First(hSnapshot, &te32))
        {
            do
            {
                // Check if the thread belongs to the target process
                if (te32.th32OwnerProcessID == targetProcessId)
                {
                    // Open the thread
                    HANDLE hThread = OpenThread(THREAD_SET_CONTEXT, 0, te32.th32ThreadID);

                    if (hThread != NULL)
                    {
                        // Inject your code here

                        CloseHandle(hThread);
                    }
                }
            } while (Thread32Next(hSnapshot, &te32));
        }

        CloseHandle(hSnapshot);
    }
}