Can Bluetooth be hacked? Here's what you need to know about how cybercriminals can target you using Bluetooth.

Bluetooth is now a widely-used technology, thanks to its inclusion in devices like smartphones and tablets. And while we've grown accustomed to using it to connect devices to our earphones, cars, and other software, Bluetooth nonetheless has its fair share of vulnerabilities.

So is it safe to use Bluetooth? How can hackers attack using Bluetooth?

In 1989, the telecommunications company, Ericsson, started to work on a wireless alternative to RS-232 serial communication. In 1996, Nokia and similar companies began to look for short-distance protocols such as Bluetooth. All these organizations formed the Bluetooth Special Interest Group (SIG).

Generally, Bluetooth technology consists of the parent device and child devices connected to it. That's a piconet. Child devices are within 10 meters of the parent device. Piconets unite, and create scatternets. The parent device here communicates with the child devices.

However, it is not possible to talk directly to child devices.

There are three basic security models in the Bluetooth protocol:

Each Bluetooth service has a security mode based on it, and provides security with three levels. Some services may use authorization and authentication, while others may only use authentication. There are two different security models for devices using this protocol.

In addition, different security levels are defined for both devices and services in the Bluetooth security architecture. There are two security levels for devices:

It is possible to exchange many files during the day with Bluetooth technology. However, if you consider the above security services and modes, you'll realize that you have to give a lot of permissions to the devices you allow to exchange files.

It is a big security problem for another device to have so many privileges over yours just because it is sending a few files. But of course, there are some precautions you can take.

Keep your Bluetooth setting in “not discoverable” (transmission disabled) and switch to “discoverable” mode only when you are using it. Leaving your smartphone or any Bluetooth device you use in discoverable mode exposes the device to Bluetooth issues. When you're out for a stroll, driving, or even walking around your office, any Bluetooth user in close range could pick up your signal and use it to access your device.

Avoid storing your critical information—such as social security numbers, identity information, serial numbers, passwords, and credit card information—on your Bluetooth-enabled devices. If you do this anyway, at least make sure those are stored on sandboxed services using complex passwords and extra layers of verification like Two-Factor Authentication (2FA).

If you are going to connect with a device via Bluetooth, make this connection in a safe place. This will limit the number of potential intruders in your vicinity.

There is a large pool of attack vectors when it comes to Bluetooth. By exploiting vulnerabilities in Bluetooth, the attacker gains unauthorized access to the victim device.

Once the attacker gains access, they use privilege escalation, i.e. using a smaller exploit to get access to the wider system and leverage control. As a result, it becomes possible to destroy evidence, attack other devices, or even take over the entire device.

Bluetooth devices are typically thought of as safe from long distances. However, this is wrong. It is possible to attack from a distance of 1500 meters with high-gain antennas, and even further, thanks to Bluetooth 5, the latest version of the technology, and developing network structures.

The general method of attackers is to generate unexpected results by transferring erroneous files. When a system receives an unexpected file and the specified security level is insufficient, it either falls into an unstable state or the system crashes. Attackers who take advantage of these situations can perform a lot of attacks on vulnerable devices. The list of what can be achieved as a result of these attacks is extensive and includes:

In short, attackers can obtain access rights to all operations you can perform at root privilege level. This situation usually occurs because Bluetooth and similar chips are directly connected to the main chip and there is no authority limitation on the main chip. At least by limiting permissions, you can restrict the root privileges during an attack.

The vulnerability, named Blueborne, published in September 2017, once again revealed how frightening Bluetooth technology can be. Thanks to this attack, it became possible to run code remotely on many devices (although remote access can be made more secure).

Blueborne had significant differences from other attacks. The aforementioned vectors require user permission. In other words, the end-user was approving things like a file transfer request, connection requests, and device trust requests. In Blueborne, however, the user did not need to give any permissions. It was possible to use it remotely.

One of the most crucial points about vulnerabilities that enable remote attacks is that they do not need any user approval. There are three main fundamental rules to this:

In other words, a hacker can carry out attacks using the vulnerability without the knowledge of the victim. The best example of this would undoubtedly be the Blueborne attack. Using Bluetooth technology, an attacker can reach the devices of an individual or even the masses, and manipulate them.

Don't leave your Bluetooth connection open, and never accept Bluetooth connections you do not trust. Keep your software up to date and remove unused Bluetooth devices from the list of trusted devices. These methods will protect you from most attacks over Bluetooth.

Of course, perfect security does not exist, and attack vectors will continue to evolve as technology does.

An engineer and software developer who is a fan of math and technology. He has always liked computers, mathematics and physics. He has developed game engine projects as well as machine learning, artificial neural networks and linear algebra libraries. Moreover continues to work on machine learning and linear matrices.

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