There are three things that I make sure I do when I’m out and about. I seek out the best coffee I can find. I make sure I use a VPN when using public Wi-Fi, and I always make sure I use a USB data blocker, otherwise known as a USB condom, whenever I use a third-party charger (such as those you find in coffee shops).
OK, first off, what on Earth is a USB condom?
A USB condom is a small dongle that adds a layer of protection between your device and the charging point you’re attaching it to.
Remember, USB isn’t just a charging protocol, it also allows data to flow back and forth, and while most of the time this data flow is safe, it is possible to create a malicious charging port that can do bad things, such as plant malware on your device or steal your data.
PortaPow USB Data Blocker
A USB-to-USB adapter that protects your connected device from juice-jacking.
And it’s not just chargers. Cables can also carry out all sorts of malicious activities.
All these cables and dongles shown below can be used to do bad things to devices.
And don’t think you can look at these cables and see the hacking wizardry inside — you can’t! They’re so easy to confuse with other cables that I keep the little orange tag on them to prevent them from getting mixed up with my regular cables.
So, back to the USB condom data blockers.
Sold by PortaPow, these are a super-simple, cheap solution to the problem of using untrusted USB charging devices. Simply plug it into a port, and any and all potential data transfer between the charger and your device is severed, putting an air gap between the USB port and your smartphone, laptop, or whatever you are charging.
For the super-paranoid, there are also transparent data blockers, the idea being that you can tell if they’ve been tampered with in any way.
The job of the USB condom is simple — to turn any USB port into a charge-only port by blocking all the data lines. Sure, you could make one yourself from a USB cable (slice it up and cut the data cables), but with these bespoke data blockers costing only about $7, it really doesn’t seem worth the hassle.
Another company that makes high-quality charge-only data-blocking cables is StarTech. These cables are one meter long and come inUSB-A-to-microUSB, USB-A-to-USB-C, and USB-A-to-USB-A. These are priced around $12, all have a cutout on the USB-A port to show no data lines, and all are marked “power only.’
Bear in mind: While a data blocker can prevent data transfer, the port might still be able to damage a device, either through accident, misconfiguration, or malicious tampering. For example, devices such as those from USB Kill can be used to, well, kill devices that are connected to them by sending high voltage through the USB port, frying the delicate electronics.
If you must use a charger, cable, or charging port that isn’t under your control, it makes sense to use a USB condom. If you want an extra layer of protection, take your own charger or power bank (or a charger that’s also a power bank, such as the Anker 733) with you and use your own cables.