A cryptographic bug in many Bluetooth firmware and operating system drivers could allow an attacker within about 30 meters to capture and decrypt data shared between Bluetooth-paired devices.
The flaw was found by Lior Neumann and Eli Biham of the Israel Institute of Technology, and flagged today by Carnegie Mellon University CERT. The flaw, which is tracked as CVE-2018-5383, has been confirmed to affect Apple, Broadcom, Intel, and Qualcomm hardware, and some Android handsets. It affects Bluetooth’s Secure Simple Pairing and Low Energy Secure Connections. Fortunately for macOS users, Apple released a patch for the flaw in July.
As the CERT notification explains, the vulnerability is caused by some vendors’ Bluetooth implementations not properly validating the cryptographic key exchange when Bluetooth devices are pairing. The flaw slipped into the Bluetooth key exchange implementation which uses the elliptic-curve Diffie-Hellman (ECDH) key exchange to establish a secure connection over an insecure channel.
This may allow a nearby but remote attacker to inject a a bogus public key to determine the session key during the public-private key exchange. They could then conduct a man-in-the-middle attack and “passively intercept and decrypt all device messages, and/or forge and inject malicious messages”.