Detect USB hardware keylogger

Question

I need to determine is there hardware keylogger that was plugged to PC with USB keyboard. It needs to be done via software method, from user-land. However wiki says that it is impossible to detect HKL using soft, there are several methods exists. The best and I think only one overiew that present in net relating that theme is "Detecting Hardware Keyloggers, by Fabian Mihailowitsch - youtube".

Using this overview I am developing a tool to detect USB hardware keyloggers. The sources for detecting PS/2 keyloggers was already shared by author and available here. So my task is to make it worked for USB only.

As suggested I am using libusb library to interfere with USB devices in system.

So, there are methods I had choosen in order to detect HKL:

1. Find USB keyboard that bugged by HKL. Note that HKL is usually invisible from device list in system or returned by libusb.
2. Detect Keyghost HKL by: Interrupt read from USB HID device, send usb reset (libusb_reset_device), read interrupt again. If data returned on last read is not nulls then keylogger detected. It is described on page 45 of Mihailowitsch's presentation
3. Time measurement. The idea is measure time of send/receive packets using control transfer for original keyboard for thousands times. In case HKL has been plugged, program will measure time again and then compare the time with the original value. For HKL it have to be much(or not so much) greater. Algorithm is:
   • Send an output report to Keyboard(as Control transfer) (HID_REPORT_TYPE_OUTPUT 0x02 )
   • Wait for ACKed packet
   • Repeat Loop (10.000 times)
   • Measure time

Below is my code according to steps of detection.

1. Find USB keyboard

libusb_device * UsbKeyboard::GetSpecifiedDevice(PredicateType pred)
{
    if (_usbDevices == nullptr) return nullptr;
    int i = 0;
    libusb_device *dev = nullptr;
    while ((dev = _usbDevices[i++]) != NULL)
    {
        struct libusb_device_descriptor desc;
        int r = libusb_get_device_descriptor(dev, &desc);
        if (r >= 0)
        {
            if (pred(desc))
                return dev;
        }
    }

    return nullptr;
}

libusb_device * UsbKeyboard::FindKeyboard()
{
    return GetSpecifiedDevice([&](libusb_device_descriptor &desc) {
        bool isKeyboard = false;
        auto dev_handle = libusb_open_device_with_vid_pid(_context, desc.idVendor, desc.idProduct);     
        if (dev_handle != nullptr)
        {
            unsigned char buf[255] = "";

            // product description contains 'Keyboard', usually string is 'USB Keyboard'            
            if (libusb_get_string_descriptor_ascii(dev_handle, desc.iProduct, buf, sizeof(buf)) >= 0)
                isKeyboard = strstr((char*)buf, "Keyboard") != nullptr;
            libusb_close(dev_handle);           
        }

        return isKeyboard;
    });
}

Here we're iterating through all USB devices in system and checks their Product string. In my system this string for keyboard is 'USB keyboard' (obviously). Is it stable way to detect keyboard through Product string? Is there other ways?

2. Detect Keyghost HKL using Interrupt read

int UsbKeyboard::DetectKeyghost(libusb_device *kbdev)
{
    int r, i;

    int transferred;
    unsigned char answer[PACKET_INT_LEN];
    unsigned char question[PACKET_INT_LEN];
    for (i = 0; i < PACKET_INT_LEN; i++) question[i] = 0x40 + i;
    libusb_device_handle *devh = nullptr;
    if ((r = libusb_open(kbdev, &devh)) < 0)
    {
        ShowError("Error open device", r);
        return r;
    }

    r = libusb_set_configuration(devh, 1);
    if (r < 0)
    {
        ShowError("libusb_set_configuration error ", r);
        goto out;
    }
    printf("Successfully set usb configuration 1\n");

    r = libusb_claim_interface(devh, 0);
    if (r < 0)
    {
        ShowError("libusb_claim_interface error ", r);
        goto out;
    }

    r = libusb_interrupt_transfer(devh, 0x81 , answer, PACKET_INT_LEN,  
                &transferred, TIMEOUT);
    if (r < 0) 
    {
        ShowError("Interrupt read error ", r);
        goto out;
    }
    if (transferred < PACKET_INT_LEN) 
    {
        ShowError("Interrupt transfer short read %", r);
        goto out;
    }

    for (i = 0; i < PACKET_INT_LEN; i++) {
        if (i % 8 == 0)
            printf("\n");
        printf("%02x, %02x; ", question[i], answer[i]);
    }
    printf("\n");

out:
    libusb_close(devh);
    return 0;
}

I've got such error on libusb_interrupt_transfer:

libusb: error [hid_submit_bulk_transfer] HID transfer failed: [5] Access denied
Interrupt read error  - Input/Output Error (LIBUSB_ERROR_IO) (GetLastError() - 1168)

No clue why 'access denied', then IO error, and GetLastError() returns 1168, which means - Element not found (What element?). Looking for help here.

3. Time measurement. Send output report and wait for ACK packet.

   int UsbKeyboard::SendOutputReport(libusb_device *kbdev) { const int PACKET_INT_LEN = 1; int r, i; unsigned char answer[PACKET_INT_LEN]; unsigned char question[PACKET_INT_LEN]; for (i = 0; i < PACKET_INT_LEN; i++) question[i] = 0x30 + i; for (i = 1; i < PACKET_INT_LEN; i++) answer[i] = 0;

   libusb_device_handle *devh = nullptr;
   if ((r = libusb_open(kbdev, &devh)) < 0)
   {
       ShowError("Error open device", r);
       return r;
   }
   
   r = libusb_set_configuration(devh, 1);
   if (r < 0) 
   {
       ShowError("libusb_set_configuration error ", r);
       goto out;
   }
   printf("Successfully set usb configuration 1\n");
   
   r = libusb_claim_interface(devh, 0);
   if (r < 0) 
   {
       ShowError("libusb_claim_interface error ", r);      
       goto out;
   }
   printf("Successfully claim interface\n");   
   
   r = libusb_control_transfer(devh, CTRL_OUT, HID_SET_REPORT, (HID_REPORT_TYPE_OUTPUT << 8) | 0x00, 0, question, PACKET_INT_LEN, TIMEOUT);
   if (r < 0) {
       ShowError("Control Out error ", r);
       goto out;
   }
   
   r = libusb_control_transfer(devh, CTRL_IN, HID_GET_REPORT, (HID_REPORT_TYPE_INPUT << 8) | 0x00, 0, answer, PACKET_INT_LEN, TIMEOUT);
   if (r < 0) {
       ShowError("Control In error ", r);
       goto out;
   }    
   

   out: libusb_close(devh); return 0; }

Error the same as for read interrupt: Control Out error - Input/Output Error (LIBUSB_ERROR_IO) (GetLastError() - 1168 )

How to fix please? Also how to wait for ACK packet?

Thank you.

UPDATE:
I've spent a day on searching and debbuging. So currently my problem is only to send Output report via libusb_control_transfer. The 2nd method with interrupt read is unnecessary to implement because of Windows denies access to read from USB device using ReadFile. It is only libusb stuff left, here is the code I wanted to make work (from 3rd example):

// sending Output report (LED)
// ...
    unsigned char buf[65]; 
        buf[0] = 1; // First byte is report number
        buf[1] = 0x80;

        r = libusb_control_transfer(devh, CTRL_OUT,
            HID_SET_REPORT/*0x9*/, (HID_REPORT_TYPE_OUTPUT/*0x2*/ << 8) | 0x00,
            0, buf, (uint16_t)2, 1000);
    ...

The error I've got:

[ 0.309018] [00001c0c] libusb: debug [_hid_set_report] Failed to Write HID Output Report: [1] Incorrect function
Control Out error  - Input/Output Error (LIBUSB_ERROR_IO) (GetLastError() - 1168)

This error occures right after DeviceIoControl call in libusb internals. What means "Incorrect function" there?