[retrac]

> not sharing data via USB

USB is a very intelligent protocol, with a microcontrollor on both ends. The controller has access to at least the driver's state, which is usually in the kernel and potentially has access to system memory.

How does your Android phone even know that data is an option to switch into when you plug it into a USB port? It has already negotiated itself to be a device on the USB bus. Your phone will probably show up in lsusb on Linux even in charging mode. (Mine does.) When you switch the phone to data mode, it changes its USB device profile, and becomes a more sophisticated attached device, from the host's perspective.

Many (most?) phones made in recent years can be USB hosts, too. This lets you connect a USB mouse and keyboard to a tablet, for example. That would open you up to all kinds of pretty simple but often quite effective attacks, like simulating a virtual keyboard and mouse and just manipulating the UI that way.

I don't know if any of these particular attacks are possible with Android right now, but many variations on these themes have been shown over the years on many platforms. USB wasn't really designed with adversarial peripherals in mind.

[epups]

Maybe I'm stupid but what I gather from this is simply that this is a potential vector, not that it is currently an actual possibility. It's akin to saying using Bluetooth is dangerous because theoretically any data on my phone can be extracted through it, while neglecting the fact that the people building a phone OS are clearly aware of that and have built-in countermeasures.