Security researchers at the Georgia Institute of Technology have built a malicious USB charger that can inject persistent, undetectable malware onto your iPhone, iPad, or other current-gen iOS device. This USB charger, called Mactans, takes less than a minute to compromise a device once it has been plugged in.

http://www.extremetech.com/extreme/157207-black-hat-hackers-break-into-any-iphone-in-under-a-minute-using-a-malicious-charger