Recent news coming from air travel security experts involves convenient USB charging stations spread around airports. While your first thought might be that you never use the USB charging station because a crowd of people always beats you to it, there’s a legitimate security risk associated with using them: “juice jacking.”

Truthfully, this type of hack has been around for years. It’s just not something known by most of the general public. Basically, an attacker can subtly modify the port to house malware that will penetrate your phone once you connect it to a port with a USB cable. The malware will affect your phone performance—more importantly, it can steal texts, emails, photos, and other data you don’t want to give out to strangers.

This doesn’t happen only at airports. Syncing your phone to a rental car’s USB port provides all sorts of access to your data. Hotel lobbies and coffee shops might set up charging stations for customers’ convenience, but think of all the people passing through, and how these places are easy pickings for data mining.

An IBM executive put it this way in a Forbes article: “Plugging into a public USB port is kind of like finding a toothbrush on the side of the road and deciding to stick it in your mouth.”

The most obvious way to avert this threat is to not use USB charging stations. This isn’t always an option for those who need access to their phone or tablet during long layovers. The safest way to charge your devices is to use your own portable charger—a wise investment, considering how inexpensive they are. They also don’t take up much room in your carry-on bag.

If you insist on using the USB charging stations in spite of the risk, get a USB condom, like the Juice-Jack Defender. It uses pins that only allows the flow of power while blocking the outgoing data stream.

Some newer smartphones have permission-only security opt-ins whenever you access external ports. However, as quickly as technology evolves, any device with even a slightly-outdated operating system can be attacked through a USB port.

To be honest, this type of malware attack isn’t common yet, but the threat exists. So, add a USB condom to your gear. And if you see a USB cable left behind at a charging station, unplug it and throw it away. Don’t use it—it could be set up with malware.