12-09-2023 | By Robin Mitchell

As more devices become integrated with Bluetooth technologies, the advertisement mechanism used by Bluetooth is giving away the location of valuables to thieves. What challenges does Bluetooth present to valuables, are there mechanisms to defend against this, and what does this mean for the future of valuables?

Portable audio loudspeaker with Bluetooth connectivity for voice calls, multimedia music enjoyment, and a mini home theater experience with mobile smartphones and computer laptops.

What challenges does Bluetooth present to valuables?

When comparing modern devices to those ten years ago, it is truly amazing to see just how much technology has changed. Processing performance has dramatically improved, energy consumption has dropped significantly, and the speed at which data can be sent across the internet has increased by several orders of magnitude.

In fact, in just a short few years, smartphones have transformed from cellular devices designed to take calls and send emails to those that govern most of our lives, being connected to government services, able to run complex web apps, and even make payments. Furthermore, cloud-based technologies now allow users to move between devices without losing valuable files or credentials, eliminating our dependency on a specific device.

One such technology that has brought about some major changes is Bluetooth; its low-energy capabilities provide devices with a short-range wireless link that has enough bandwidth for file sharing and audio. Further advances in Bluetooth have even allowed for it to be used as a tracking signal for lost property, something which has personally helped me on multiple occasions.

But for all the benefits that Bluetooth introduces, the dangers of theft and privacy continue to grow, so much so that tech companies have already started to work on solutions to counteract these issues. 

Primarily, the danger that Bluetooth presents is that most devices are typically put in a discoverable mode, whereby other Bluetooth devices can find them. This mode is essential for allowing headphones, speakers, and cameras to automatically connect without needing to follow complex setup procedures each time. Furthermore, each device has a unique ID, meaning that in a sea of identical phones or laptops, each device is individually recognisable. 

This advertising nature of Bluetooth means that it is very trivial for criminals to track down devices of particular importance. To make matters worse, the use of names and manufacturing IDs means that not only can devices be identified, but their value is also estimated (such as Robins iPhone 15). 

The final nail in the coffin, however, is that not only does Bluetooth allow criminals to track valuables, but those that carry them. Even if the exact devices that a victim is using are unknown, the combination of following a victim and using a Bluetooth logger can reveal which devices were visible for the longest time, thus indicating which devices are theirs

A criminal who is exceptionally clever could even install Bluetooth sniffers across a large space powered by a small battery. As these devices are not transmitting, they can easily record data while using very little power, thus operating for extended periods of time once installed. Furthermore, their lack of transmission would make them hard to spot, and they could easily be hidden in bins, signs, cupboards, and roofs of buildings.

According to a recent news report, tech-savvy thieves are utilising Bluetooth to decide if cars are worth breaking into. This highlights the growing concerns around Bluetooth security and the need for more robust protective measures.

Are there mechanisms to defend against this?

Defending against Bluetooth tracking is no small feat, as Bluetooth is required for numerous wireless devices. For example, just walking down the street with a pair of wireless headphones will need Bluetooth to be turned on. 

The most obvious defence against Bluetooth tracking is turning off Bluetooth outright. Unless Bluetooth is absolutely needed, turning Bluetooth off while out will prevent any tracker from seeing devices, but it is also possible that Wi-Fi can give away one’s location too (albeit more difficult than Bluetooth).

One option that engineers could explore is the idea of decreasing the frequency at which devices advertise themselves. By only having devices announce their existence once a minute or so, it becomes harder to track a device, as Bluetooth only has a range of a few meters or so.

This short range is another option that engineers can deploy: range limiting. While long-range Bluetooth is extremely useful, it is also able to give away one’s position over a far greater distance. Thus, by significantly reducing the power of Bluetooth transmitters, a tracking device would need to be in close proximity, thus being more likely to be revealed.

While not suitable for defending against self-advertised devices, it is also possible to protect individuals against tracking devices placed upon their person with their knowledge by integrating Bluetooth sniffing into personal smartphones. Any unrecognised Bluetooth device that has stayed in close proximity for an extended period of time can be detected and alert the user. From there, the device can be found and destroyed, but this doesn’t defend against passive Bluetooth sniffing.

The DCMS report on ensuring future wireless connectivity needs emphasises the importance of security in wireless technologies, including Bluetooth. As we become more reliant on these technologies, ensuring their security becomes paramount.

What does this mean for the future of valuables?

With regard to valuables being stolen, it is likely that engineers will continue to develop solutions that simply brick stolen devices, making them unusable. For example, Apple iPhones are renowned for being secure in that stolen devices are completely useless. By contrast, many Android devices are easily wiped and can be resold with little difficulty (in some cases, stolen devices can be unlocked, giving the thief access to all the phone’s data).

Some manufacturers are even exploring the idea of software locking in devices such as power tools. If such devices are given wireless capabilities, it becomes possible for them to be security-locked if stolen, thereby making stolen devices worthless.

The only other option for locking devices is to outright move away from Bluetooth as a connectivity option. However, this is easier said than done, and the dominance of Bluetooth makes this highly problematic (with devices not being compatible with others). Wi-Fi is one possibility, but as it isn’t designed for connecting multiple devices simultaneously with ease, it would require some fundamental changes.

Overall, Bluetooth is a double-edged sword in that it provides numerous plenty of benefits, all while introducing some serious challenges. As technology progresses, it is likely that engineers will eventually find solutions to the problems of theft and tracking. 

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By Robin Mitchell

Robin Mitchell is an electronic engineer who has been involved in electronics since the age of 13. After completing a BEng at the University of Warwick, Robin moved into the field of online content creation, developing articles, news pieces, and projects aimed at professionals and makers alike. Currently, Robin runs a small electronics business, MitchElectronics, which produces educational kits and resources.