Researchers raise privacy concerns about Bluetooth Low Energy devices

Researchers at Context Information Security have raised privacy concerns about a growing number of devices using Bluetooth Low Energy (BLE) technology.

Incompatible with traditional Bluetooth, BLE was developed by the Bluetooth Special Interest Group (SIG) as a personal wireless technology that is rapidly finding its way into personal devices.

These include mobile phones, Apple’s iBeacons and a growing number of wearable devices that monitor activity, fitness and heartbeats that typically use BLE to communicate with mobile apps.

The researchers have developed an app of their own that demonstrates how easy it is to capture, monitor and record BLE signals.

Publication of the Context findings comes just a week after China banned its armed forces from wearing internet-connected wearable tech.

The Chinese military’s official newspaper said any wearable technology that can process and transmit data could be used to track military personnel or to reveal military secrets, according to a BBC report.

“Many people wearing fitness devices don’t realise they are broadcasting constantly and that these broadcasts can often be attributed to a unique device,” Context senior researcher Scott Lester told the security firm’s Oasis symposium in London.

“Using cheap hardware or a smartphone, it could be possible to identify and locate a particular device that belongs to a celebrity, politician or senior business executive within 100 metres in the open air.

“This information could be used for social engineering as part of a planned cyber attack or for physical crime by knowing people's movements,” he said.  

BLE was released in 2010 for a range of new applications that rely on constantly transmitting signals without draining the battery.

Lester said that like other network protocols it relies on identifying devices by their media access control (MAC) addresses, but while most BLE devices have a random MAC address, Context researchers found that in most cases the MAC address does not change.

“My own fitness tracker has had the same MAC address since we started the investigation, even though it’s completely run out of battery once,” he said.

Sometimes the transmitted packets also contain the device name, said Lester, such as the "Garmin Vivosmart #12345678", or even give the name of the user, such as "Scott’s Watch".

BLE is also increasingly used in mobile phones and is supported by iOS 5 and later, Windows Phone 8.1, Windows 8, Android 4.3 and later, as well as the BlackBerry 10.

The Bluetooth SIG has predicted that by 2018, more than 90% of Bluetooth-enabled smartphones are expected to support BLE, while the number of Bluetooth-enabled cars is expected to top 50 million.

Lester said iBeacons, which also transmit BLE packets to identify a location, are already used in Apple Stores to tailor notifications to visiting customers, while British Airways and Virgin use iBeacons with their boarding pass apps to welcome passengers walking into the lounge with the Wi-Fi password. 

House of Fraser is also trialling iBeacons on mannequins to allow customers to look at the clothes and their prices on their phones.

The current model for iBeacons is that they should not be invasive, which means an iBeacon-aware app needs to be running to detect and respond to a beacon.

“However, it doesn’t take much imagination to think of a phone manufacturer providing handsets with an iBeacon application already installed, so your phone alerts you with sales notifications when you walk past certain shops,” said Lester.

The current version 4.2 of the Bluetooth Core Specification makes it possible for BLE to implement public key encryption and keep packet sizes down, while also supporting different authentication schemes.

“Many BLE devices simply can’t support authentication and many of the products we have looked at don’t implement encryption, as this would significantly reduce battery life and increase the complexity of the application,” said Lester.

He said it is clear that BLE is a powerful technology, which is increasingly being put to a wide range of uses.

“While the ability to detect and track devices may not present a serious risk in itself, it certainly has the potential to compromise privacy and could be part of a wider social engineering threat. It is also yet another demonstration of the lack of thought that goes into security when companies are in a rush to get new technology products to market,” said Lester.