Mobile apps that work with Bluetooth devices have an inherent design flaw that makes them vulnerable to hacking, new research has found.

The problem lies in the way Bluetooth Low Energy devices a type of Bluetooth used by most modern gadgets communicate with the mobile apps that control them.

Research found it to be a consistent problem among Bluetooth low energy devices when communicating with mobile apps.

Consider a wearable health and fitness tracker, smart thermostat, smart speaker or smart home assistant.

Each first communicates with the apps on your mobile device by broadcasting something called a UUID a universally unique identifier.

That identifier allows the corresponding apps on your phone to recognize the Bluetooth device, creating a connection that allows your phone and device to talk to one another.

But that identifier itself is also embedded into the mobile app code. Otherwise, mobile apps would not be able to recognize the device.

However, such UUIDs in the mobile apps make the devices vulnerable to a fingerprinting attack, research team found.

At a minimum, a hacker could determine whether you have a particular Bluetooth device, such as a smart speaker, at your home, by identifying whether or not your smart device is broadcasting the particular UUIDs identified from the corresponding mobile apps.

But in some cases in which no encryption is involved or encryption is used improperly between mobile apps and devices, the attacker would be able to ‘listen in’ on your conversation and collect that data.”

Still, that doesn’t mean you should throw your smartwatch away.

After a team realized Bluetooth devices had this built in vulnerability, they wanted to see how widespread it might be in the real world. They built a “sniffer” a hacking device that can identify Bluetooth devices based on the broadcasting messages sent by the devices.

The typical understanding is that Bluetooth Low Energy devices have signals that can only travel up to 100 meter researcher said. But we found that with a simple receiver adapter and amplifier, the signal can be ‘sniffed’ (or electronically found) much farther up to 1,000 meters away.

Those that were vulnerable to unauthorized access had issues with the initial fingerprinting between device and phone app that put them at risk of hacking.

These devices know a lot about us they are the wearable technologies that track our steps and our heart rates; the speakers that “hear” us and play songs we want to hear, or give us an easy way to order new things off the internet.

The research focuses on vulnerabilities in tech, trying to identify those potential security gaps before they become true security problems.