USB devices may be leaking information

Researchers from the University of Adelaide have revealed that USB connections are highly vulnerable to information ‘leakage’, making them even less secure than previously thought.

“USB-connected devices include keyboards, card swipers and fingerprint readers, which often send sensitive information to the computer,” explained project leader Dr Yuval Yarom.

“It has been thought that because that information is only sent along the direct communication path to the computer, it is protected from potentially compromised devices.

“But our research showed that if a malicious device or one that’s been tampered with is plugged into adjacent ports on the same external or internal USB hub, this sensitive information can be captured. That means keystrokes showing passwords or other private information can be easily stolen.”

Dr Yarom said this “channel-to-channel crosstalk leakage” is analogous with water leaking from pipes, noting, “Electricity flows like water along pipes — and it can leak out.

“In our project, we showed that voltage fluctuations of the USB port’s data lines can be monitored from the adjacent ports on the USB hub.”

The leak was discovered after the researchers used a modified novelty plug-in lamp with a USB connector to ‘read’ every keystroke from the adjacent keyboard USB interface. The data was sent via Bluetooth to another computer.

After conducting tests on more than 50 different computers and external USB hubs, the researchers found that over 90% of them leaked information to an external USB device. And with previous research showing that 75% of USB sticks dropped on the ground are picked up and plugged into a computer, Dr Yarom noted that these devices could have been tampered with to send a message via Bluetooth or SMS to a computer anywhere in the world.

“The main take-home message is that people should not connect anything to USB unless they can fully trust it,” he said. “For users, it usually means not to connect to other people’s devices. For organisations that require more security, the whole supply chain should be validated to ensure that the devices are secure.”


Dr Yarom said the long-term solution is a redesign of USB connections to make them more secure. In the meantime, he said Bluetooth is a more secure way of transferring information.

“The USB has been designed under the assumption that everything connected is under the control of the user and that everything is trusted — but we know that’s not the case,” he said. “The USB will never be secure unless the data is encrypted before it is sent.”

The research is being presented at the 26th USENIX Security Symposium in Vancouver next week.