Charging a mobile device by plugging it into a computer initiates a connection that involves an exchange of data between the devices. The amount of data transferred depends on the mobile device, but typically includes an abundance of identifying information. In addition, the connection not only allows the computer to collect your data, but it can also install unwanted files, including malware and ransomware.
The same risk is present when users plug into a public charging station. Plugging into a fraudulent charging station gives cybercriminals access to the mobile device via the connection. Shaikh Rafia “Charging Smartphones with USB Cable Could Lead to Data Thefts and Malware Infections,” wccftech.com (May 24, 2016).
Source: The HartfordHelp June 21, 2016