Is It Dangerous to Use a Public USB Port?

Every now and then, a specific tech warning makes headlines: “Don’t use public USB ports.” The warning comes from the media, government agencies, even the FBI, who all allege that plugging your smartphone into a public USB port, such as one you’d find at an airport, poses a security risk. But is that actually true?

The short answer? Yes, but you probably don’t need to worry about it. Here’s the deal: The danger with public USB ports is that bad actors could add malicious software to the port undetected. Because USB both charges devices and sends data between them, your USB plug could then download that malicious software to your device. It’s a practice called “juice jacking,” and it is possible to pull off.

The thing is, the only publicly disclosed instances of juice jacking have occurred in controlled environments as part of demonstrations of the practice itself—not somewhere like an airport. This proves that juice jacking is theoretically possible, but it doesn’t mean that hackers are actively targeting travelers in airports. For one, it’d be largely impractical for hackers to buy plane tickets and install malware on random USB ports across the airports they visit. Airports are also under constant surveillance: If there were users tampering with USB ports in a tangible way, these ports would likely be removed.

If you don’t feel comfortable using these ports with this theoretical risk, avoid them. Instead, you can safely use any standard outlet, which will not transmit data. Just remember to pack your power adapter in addition to your USB cable. But on the flip side, you can take advantage of some simple security hacks to use these ports with some peace of mind. For starters, buy USB cables that are charging only, and cannot pass data between devices. You could also buy a data blocker for your existing USB cable, which achieves the same goal.

Your smartphone likely has protections in place, too. iPhones, for example, ask your permission to share data when plugging into a new USB source. If you don’t grant it, any data requests—malicious or not—will be blocked.