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Bluetooth KNOB Attack Details

Posted By : Ken Colburn of Data Doctors on August 22, 2019


How dangerous is the KNOB Bluetooth vulnerability and what should I be doing to protect my phone?


This question was answered on August 22, 2019. Much of the information contained herein may have changed since posting.

Security researchers recently discovered a way to intercept a Bluetooth connection between two devices, leading to the ability to plainly view all of the data being transmitted between the two devices.

The ‘attack’ was successful on 17 different kinds of Bluetooth chips on 24 different devices that they tested, which means that every popular brand of device that uses Bluetooth is vulnerable.

It’s being referred to as the KNOB (Key Negotiation of Bluetooth) attack because it changes the initial connection process when two devices are being paired together.

In essence, the security researchers figured out how to lower the encryption level used to keep Bluetooth connections secured, by jumping in during the initial negotiation process prior to making a connection.

The Bluetooth Special Interest Group, an International organization in charge of Bluetooth standards issued a security warning and developed the basic fix that will they provided to hardware manufacturers to implement and distribute.

Proof of Concept
While many technology reporters are creating lots of scary sounding headlines about how unsafe Bluetooth is now that this vulnerability is public, it’s a bit overblown.

The security researchers were able to create a specific situation in their labs to take advantage of the exploit, which only proved that it could be done, not that it is being done.

In order to actually pull this off in real life, the perpetrator would need a really specialized and expensive piece of equipment, be relatively nearby and could only exploit the connection at the very moment that the two devices where attempting to pair with one another.

Even if they were to be in the right place at the right time, if you’re not using Bluetooth to transmit sensitive data, all they would intercept is what song you’re listening to on your ear buds or in your car.

It’s just too complicated and random for it to be attractive to sophisticated cyber-thieves, so despite the scary headlines, you’re not suddenly vulnerable because you use a Bluetooth headset, keyboard or mouse.

This vulnerability does not apply to newer BLE (Bluetooth Low Energy) devices like fitness devices, proximity sensors or medical devices.

The Fix Is In…
The companies that make Bluetooth chips were actually notified last November so they could work on creating patches before the information became public.

Most major device manufacturers have been including the fix in their recent updates, so if you keep your devices updated regularly, it’s quite possible that you already have the fix installed.

Turn Bluetooth Off
There are other serious Bluetooth vulnerabilities such as BlueBorne that exist and new methods will likely be discovered in the future, so it’s always a good idea to turn off Bluetooth when you aren’t using it.

Another small benefit to turning it off is that it helps with precious battery life. A typical Bluetooth radio is routinely scanning for devices to connect to that come into range.

Bluetooth wasn’t developed with security as it’s primary focus – hopefully that will change – so expect to hear about more discoveries down the road and keep all your devices updated.

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Posted by Ken Colburn of Data Doctors on August 22, 2019


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