“To avoid being a victim in the first place, Coulson encourages adopting newer USB technology (such as USB C) or purchasing charging-only cables, which don’t allow data extraction. Wireless chargers are a more secure option, Chugh said, with instances of tampering on such devices “pretty much nonexistent.” When you plug a smartphone into a USB port, it also might ask whether you trust the device you’ve connected to. That’s a signal that the USB could be doing more than just charging. Unless you’ve connected to your personal computer, you should say no, experts say.”
Source : FBI warns of public phone chargers: What to know about juice jacking – The Washington Post