Most people have heard about credit card skimmers. In SW Florida they are a scourge at gas pumps. However, there’s another attack you might not know about that can hijack your cell phone. It’s called “Juice Jacking” because when you need power (Juice), a public USB charger can attack (Jack) your phone over the data cable. iOS and Android have features to stop this, but new attacks are being developed all the time.
For once, this is a security story with good news! If you want complete security, there is a low-tech fix that will 100% protect your phone.
A standard USB cable has 4 pins, arranged with Power and Ground on the two outside pins, and Data in the middle. If you want power and don’t want data, then disconnect the data pins. There are many devices that will do this for you. A popular Google search term is “USB Data Blocker“.
I particularly like a device called the Pure USB Data Blocker. It has a clear case, so you can visually ensure it does exactly what it claims.
There is a small downside to this blunt approach, but with some smart electronics, it can be overcome. Many devices use the data pins to communicate with the charger. If the device can’t negotiate with the charger it will limit the charge current to avoid problems. This can cause slow charging. To solve this problem, more advanced data blockers will use smart circuitry to negotiate with the charger. The PortaPow 3rd Gen Data Blocker automatically switches between Apple, Universal, and Samsung standards to ensure compatibility with your device.
For less than $7 you can stop hijackers when you choose to charge from a public USB station. You can charge at full speed with a smart data blocker, or if you are extra cautious, use a clear-cased version with no electronics at all. In fact, with a couple of connectors and a soldering iron, it’s pretty easy to make your own.