ABSTRACT
The Universal Serial Bus (USB) connection has become the
de-facto standard for both charging and data transfers for
smart phone devices including Google’s Android and Apple’s
iPhone. To further enhance their functionality, smart
phones are equipped with programmable USB hardware and
open source operating systems that empower them to alter
the default behavior of the end-to-end USB communications.
Unfortunately, these new capabilities coupled with
the inherent trust that users place on the USB physical connectivity
and the lack of any protection mechanisms render
USB a insecure link, prone to exploitation. To demonstrate
this new avenue of exploitation, we introduce novel attack
strategies that exploit the functional capabilities of the USB
physical link. In addition, we detail how a sophisticated adversary
who has under his control one of the connected devices
can subvert the other. This includes attacks where a
compromised smart phone poses as a Human Interface Device
(HID) and sends keystrokes in order to control the victim
host. Moreover, we explain how to boot a smart phone
device into USB host mode and take over another phone
using a specially crafted cable. Finally, we point out the underlying
reasons behind USB exploits and propose potential
defense mechanisms that would limit or even prevent such