Experts from Kaspersky Lab conducted an experiment to demonstrate the risks for charging mobile devices with untrusted USB charging points and PCs. The researchers analyzed a number of smartphones running various versions of Android and iOS operating systems in order to understand which kind of data it is possible to exfiltrate from such devices while connected to a computer for charging. The results of the tests are very interesting, mobile devices share a lot of data to the computer while they are connected, in particular during the handshake phase.”]
Source: http://securityaffairs.co/wordpress/48044/hacking/charging-mobile-devices-risks.html