commoncriteria / mobile-device

Protection Profile for Mobile Device Fundamentals
The Unlicense
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USB Tethering update (FMT_SMF_EXT.1 #41) #60

Open woodbe opened 3 years ago

woodbe commented 3 years ago

The USB tethering option provides a selection of authentication options (pre-shared key, password or no auth), but these are just copied from the hotspot and are not really applicable to USB. The only way I have seen to do USB tethering with some sort of passcode is to require additional software (on both the client and the mobile device as the server) that would provide the authentication as it isn't something that is built into the USB tethering functions.

I do not want to remove USB tethering, but it should be focused on when/how it is enabled, as the option. To use USB tethering, you generally have to do follow these steps once the USB cable is connected:

  1. Authenticate to the mobile device (using the normal lock screen)
  2. Open the settings for tethering, and turn it on

If you disconnect the cable (say to walk away with the phone) and then come back, you need to do these steps again, you cannot just plug the cable back in and start tethering the connection. While there may not be authentication on the USB connection itself, the service is only available once it has been authorized by the user. Even if the user has a swipe password (for Android which is basically an unlocked device, and not a CC-valid configuration), the user must still do these steps. To be clear, the device can lock after the connection has been turned on and remain working. This is all about the initial authorization, not ongoing connectivity which is assumed to be allowed until either the tethering function is turned off (after the user unlocks the device) or the cable is disconnected.

That all said, I can see the possibility of having a USB tethering system where it is just enabled and could work without specifically being enabled (I guess), and I could see (maybe), something where there could be some type of limits to the devices allowed to connect (maybe the VID or something for the type of laptop), but none of these are presented here as options.

I think the selections should be changed to these:

Today I think only device authentication is in the market, but the USB device ID is used to restrict other types of connections for other services, so it may be able to be used here as well, and would provide some other options.