New BLUFFS Bluetooth Attack Expose Devices to Adversary-in-the-Middle Attacks

New BLUFFS Bluetooth Attack Expose Devices to Adversary-in-the-Middle Attacks

New research has unearthed multiple novel attacks that break Bluetooth Classic’s forward secrecy and future secrecy guarantees, resulting in adversary-in-the-middle (AitM) scenarios between two already connected peers.

The issues, collectively named BLUFFS, impact Bluetooth Core Specification 4.2 through 5.4. They are tracked under the identifier CVE-2023-24023 (CVSS score: 6.8) and were responsibly disclosed in October 2022.

While forward secrecy in key-agreement cryptographic protocols ensures that past communications are not revealed, even if the private keys to a particular exchange are revealed by a passive attacker, future secrecy (aka backward secrecy) guarantees the confidentiality of future messages should the past keys get corrupted.

In other words, forward secrecy protects past sessions against future compromises of keys.

The attack works by weaponizing four architectural vulnerabilities, including the aforementioned two flaws, in the specification of the Bluetooth session establishment process to derive a weak session key, and subsequently brute-force it to spoof arbitrary victims.

Bluetooth Attack

The disclosure comes as ThreatLocker detailed a Bluetooth impersonation attack that can abuse the pairing mechanism to gain wireless access to Apple macOS systems via the Bluetooth connection and launch a reverse shell.