OpenProcess error code 5

Пытаюсь записать байты в память но не могу открыть процесс. handle возвращает 0, а Marshal.GetLastWin32Error() возвращает 5. Из System Error Codes (0-499) следует, что 5 это

ERROR_ACCESS_DENIED

5 (0x5)

Access is denied.

но пользователь является администратором, и владельцем указан администратор этого компьютера:

    internal Process _process { get; private set; }

    [DllImport("kernel32.dll", SetLastError = true)]
    public static extern IntPtr OpenProcess(
    ProcessAccessFlags processAccess,
    bool bInheritHandle,
    int processId
    );

    [DllImport("kernel32.dll", SetLastError = true)]
    [ReliabilityContract(Consistency.WillNotCorruptState, Cer.Success)]
    [SuppressUnmanagedCodeSecurity]
    [return: MarshalAs(UnmanagedType.Bool)]
    static extern bool CloseHandle(IntPtr hObject);

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

    [Flags]
    public enum ProcessAccessFlags : uint
    {
        All = 0x001F0FFF,
        Terminate = 0x00000001,
        CreateThread = 0x00000002,
        VirtualMemoryOperation = 0x00000008,
        VirtualMemoryRead = 0x00000010,
        VirtualMemoryWrite = 0x00000020,
        DuplicateHandle = 0x00000040,
        CreateProcess = 0x000000080,
        SetQuota = 0x00000100,
        SetInformation = 0x00000200,
        QueryInformation = 0x00000400,
        QueryLimitedInformation = 0x00001000,
        Synchronize = 0x00100000
    }

    private IntPtr OpenProcess(Process proc, ProcessAccessFlags flags)
    {
        return OpenProcess(flags, false, proc.Id);
    }

    private void WriteBytes()
    {
        var adress = (UIntPtr) 0x88406F0C;
        byte[] bytes = { 0x74, 0x27, 0x00, 0x00 };
        var size = (UIntPtr) 4;
        var writtenBytes = new UIntPtr();
        var handle = OpenProcess(_process, ProcessAccessFlags.All);
        if (handle == IntPtr.Zero)
        {
            MessageBox.Show(Marshal.GetLastWin32Error().ToString());
        }
        WriteProcessMemory(handle, adress, bytes, size, out writtenBytes);
        CloseHandle(handle);
    }