What Is a USB Condom? How Does It Work?

Though you may not think too much about what’s going on when your phone’s plugged in, your USB cable is doing double duty: It charges your phone and transfers data between devices.

The bad news: Hackers can exploit this pathway into your device. They may do this by loading a public USB port with malware and waiting for you to plug in, whether that’s at a free airport charging station or at a hotel. While there’s no way to tell whether a USB port is malicious, you can protect your device with a “USB condom.”

“The USB condom breaks the data connection,” said Jim Goepel, CEO of Fathom Cyber, a cybersecurity consulting company. “It only allows electricity to flow through and charge the phone. It doesn’t let any data flow through.”

Here’s how this preventive gadget can protect your device from a bad case of malware.

What is a USB condom?

A USB condom is a small dongle you can attach to a USB connector before plugging it in to a USB port. The connector is the flat, male end of the cable that’s plugged in to a charger or data source. Also called a data blocker, the USB condom temporarily disables the pins that transfer data but allows electricity to flow through.

“USB condoms are meant for people who are security-conscience,” said Goepel, who gives them to his kids to use. His cybersecurity company also hands them out as freebies. Without the condom, the USB cable can transmit data from your device to whatever it’s connected to. From there, the hacker may be able to steal your personal information or control your phone using malware. Cybersecurity experts have shown hackers can rig these charging stations and penetrate devices through a method called juice jacking.

Some cybersecurity experts, however, argue juice jacking is not a serious threat. “In the nearly 10 years since it was first discussed as a theoretical possibility, there has been no reported, let alone confirmed, case,” said Anne P. Mitchell, attorney and dean of cybersecurity and cyberlaw at Lincoln Law School of San Jose.

How do USB condoms work?

You’ll have to decide whether it’s worth it to buy a USB condom and use it at public charging stations. They’re small, easy to tote around and range in price from about $7 to $15. You can buy one on Amazon.com or at a manufacturer’s website. So even if you never encounter a compromised USB port, being careful won’t break the bank.

To use one, plug in the male end of your USB cable to the female end of the data blocker. Then plug in the male end of the data blocker to the public charging station. The USB condom will act as a middleman between your device and the charging station.

How can I protect myself from cyber attack?

When it comes to cybersecurity, always protect your devices against potential malware attacks. But there are other ways to stay vigilant.

If you see suspicious text messages or phone calls after using a public charging station, it’s best not to answer them. You can use a reverse phone lookup tool to potentially learn more about who’s trying to contact you. An email lookup service can also help if you’ve started receiving phishing emails.

It’s best to charge your phone using an AC wall outlet, as these can’t be compromised. Goepel recommends traveling with a fully charged power bank, a good USB cable and a power block to use with an AC wall outlet. “If you have those three things,” Goepel said, “most of the time you’re in good shape and you don’t have to use a public USB outlet anyway.”