Tuesday, July 24, 2018

Bluetooth Vulnerability

  Bluetooth implementations may not sufficiently validate elliptic curve parameters during Diffie-Hellman key exchange.


Bluetooth firmware or operating system software drivers may not sufficiently validate elliptic curve parameters used to generate public keys during a Diffie-Hellman key exchange, which may allow a remote attacker to obtain the encryption key used by the device.


CWE-325: Missing Required Cryptographic Step - CVE-2018-5383
Bluetooth utilizes a device pairing mechanism based on elliptic-curve Diffie-Hellman (ECDH) key exchange to allow encrypted communication between devices. The ECDH key pair consists of a private and a public key, and the public keys are exchanged to produce a shared pairing key. The devices must also agree on the elliptic curve parameters being used. Previous work on the "Invalid Curve Attack" showed that the ECDH parameters are not always validated before being used in computing the resulted shared key, which reduces attacker effort to obtain the private key of the device under attack if the implementation does not validate all of the parameters before computing the shared key.

In some implementations, the elliptic curve parameters are not all validated by the cryptographic algorithm implementation, which may allow a remote attacker within wireless range to inject an invalid public key to determine the session key with high probability. Such an attacker can then passively intercept and decrypt all device messages, and/or forge and inject malicious messages.

Both Bluetooth low energy (LE) implementations of Secure Connections Pairing in operating system software and BR/EDR implementations of Secure Simple Pairing in device firmware may be affected. Bluetooth device users are encouraged to consult with their device vendor for further information.

Since the vulnerability was identified, the Bluetooth SIG has updated the Bluetooth specifications to require validation of any public key received as
part of public key-based security procedures, thereby providing a remedy to the vulnerability from a specification perspective. In addition, the Bluetooth SIG has added testing for this vulnerability within its Bluetooth Qualification Program.  The Bluetooth SIG has also released a public statement regarding the vulnerability.


An unauthenticated, remote attacker within range may be able to utilize a man-in-the-middle network position to determine the cryptographic keys used by the device. The attacker can then intercept and decrypt and/or forge and inject device messages.


Apply an update

Both software and firmware updates are expected over the coming weeks. Affected users should check with their device vendor for availability of updates.

Vendor Information

VendorStatusDate NotifiedDate Updated
AppleAffected18 Jan 201823 Jul 2018
BroadcomAffected18 Jan 201819 Jun 2018
IntelAffected18 Jan 201823 Jul 2018
QUALCOMM IncorporatedAffected18 Jan 201806 Feb 2018
MicrosoftNot Affected06 Feb 201820 Jul 2018
Android Open Source ProjectUnknown18 Jan 201818 Jan 2018
Bluetooth SIGUnknown06 Feb 201806 Feb 2018
GoogleUnknown19 Mar 201819 Mar 2018
Linux KernelUnknown05 Mar 201805 Mar 2018