Need

Enhanced data authenticity validation and secure device binding

Context

• Usage of C# for developing robust and efficient applications
• Usage of Microsoft.AspNetCore.Mvc for building web applications using the ASP.NET Core MVC framework
• Usage of System.Threading.Tasks for asynchronous programming in .NET

Description

Non compliant code

        public class DeviceController : Controller
{
    private readonly IDeviceService _deviceService;

    public DeviceController(IDeviceService deviceService)
    {
        _deviceService = deviceService;
    }

    [HttpPost]
    public async Task PairDevices(string deviceId1, string deviceId2)
    {
        var device1 = await _deviceService.GetDeviceById(deviceId1);
        var device2 = await _deviceService.GetDeviceById(deviceId2);

        if(device1 == null || device2 == null)
        {
            return NotFound();
        }

        device1.PairWith(device2);

        await _deviceService.UpdateDevice(device1);
        await _deviceService.UpdateDevice(device2);

        return Ok();
    }
}
        
        

The above code represents an ASP.NET Core Controller DeviceController which has a PairDevices method. This method takes two device IDs as parameters, fetches the devices from a service, and pairs them together.

The vulnerability lies in the fact that there is no form of validation or authentication to ensure that the devices being paired are indeed the correct devices. The method simply takes the IDs as input and pairs the corresponding devices together.

This lack of validation and authentication makes the system susceptible to misbinding attacks. An attacker could potentially pair two devices that they shouldn't have access to, leading to unauthorized access and control of the devices.

Furthermore, the lack of verifiable identifiers means that there is no way to ensure that the device IDs provided as input are indeed linked to the correct devices. This could allow an attacker to spoof device IDs and pair devices that they otherwise wouldn't have access to.

The PairDevices method needs to implement some form of authentication and validation to ensure that the devices being paired are the correct ones and that the user has the necessary permissions to do so.

Steps

• Implement a secure device pairing protocol that includes data authenticity validation.
• Generate verifiable identifiers for each device during the pairing process.
• Ensure that the device pairing protocol uses strong cryptographic algorithms for secure communication.
• Implement a mechanism to securely store and retrieve device identifiers.
• Regularly update and patch the device pairing protocol to address any known vulnerabilities.

Compliant code

        public class DeviceController : Controller
{
    private readonly IDeviceService _deviceService;
    private readonly IDevicePairingService _devicePairingService;

    public DeviceController(IDeviceService deviceService, IDevicePairingService devicePairingService)
    {
        _deviceService = deviceService;
        _devicePairingService = devicePairingService;
    }

    [HttpPost]
    public async Task PairDevices(string deviceId1, string deviceId2)
    {
        var device1 = await _deviceService.GetDeviceById(deviceId1);
        var device2 = await _deviceService.GetDeviceById(deviceId2);

        if(device1 == null || device2 == null)
        {
            return NotFound();
        }

        // Generate verifiable identifiers for each device
        var device1Identifier = _devicePairingService.GenerateIdentifier(device1);
        var device2Identifier = _devicePairingService.GenerateIdentifier(device2);

        // Validate the identifiers
        if (!_devicePairingService.ValidateIdentifier(device1Identifier) || !_devicePairingService.ValidateIdentifier(device2Identifier))
        {
            return BadRequest("Invalid device identifiers");
        }

        // Pair the devices using a secure protocol
        _devicePairingService.PairDevices(device1, device2, device1Identifier, device2Identifier);

        await _deviceService.UpdateDevice(device1);
        await _deviceService.UpdateDevice(device2);

        return Ok();
    }
}
        
        

The updated code now includes a secure device pairing protocol that validates data authenticity. This is achieved by generating verifiable identifiers for each device during the pairing process. The identifiers are then validated to ensure they are correct.

The IDevicePairingService is a new service that is responsible for the secure pairing of devices. It generates and validates the identifiers, and pairs the devices using a secure protocol. This service should use strong cryptographic algorithms to ensure the security of the communication.

The PairDevices method in the DeviceController now uses this service to pair the devices. It first retrieves the devices from the IDeviceService, then generates and validates the identifiers using the IDevicePairingService. If the identifiers are valid, it pairs the devices using the secure protocol.

The devices are then updated in the IDeviceService. If any of these steps fail, an appropriate HTTP response is returned.

This solution ensures that the device pairing protocol is secure and resistant to misbinding attacks. It also provides a mechanism to securely store and retrieve device identifiers. Regular updates and patches should be applied to the device pairing protocol to address any known vulnerabilities.

References

• 377. Insufficient data authenticity validation - Device Binding