Bluetooth is flawed: Vulnerabilities permit eavesdropping

Bluetooth, as it turns out, is not as secure as it appears. Researchers have identified a significant security flaw with Bluetooth versions 4.2 through 5.4. Under specific conditions, this flaw permits unauthorized eavesdropping on communication between two paired devices.

Issues with the Bluetooth interface, collectively referred to as BLUFFS, arise from the usage of a somewhat careless connection security mechanism between two devices. As reported by The Hacker News and based on the findings of EURECOM experts, in certain favorable circumstances, including physical nearness, it is possible to eavesdrop on the communication between two paired devices. This type of interference is a Man-In-The-Middle attack.

An attacker trying to impersonate one of the paired devices can exploit this weakness by manipulating the key handling and generation mechanism. The attacker can force the device to establish the smallest possible key, using the input values dictated by the attacker. Consequently, the same key used to encrypt the Bluetooth communication could potentially be used for many subsequent pairs of devices within close range of the victim's equipment, thus making it susceptible to being broken by brute force.

In response to these vulnerabilities, a comment from Bluetooth SIG has already been published online. They advise manufacturers to ensure only secure connections in devices and refuse attempts to establish communication using excessively short encryption keys (less than 7 or 16 octets, depending on the case).

Considering that this issue affects Bluetooth versions starting from the older 4.2 version, numerous devices on the market are potentially at risk. However, it should be noted that because the range of Bluetooth connection is limited, an attack would require physical proximity to the target devices.