©2019 Security Unleashed | New Delhi

  • Animesh Gupta

The Bluetooth - “Device Snooping Bug”



Researchers from the Technion – Israel Institute of Technology have disclosed a serious vulnerability in the Bluetooth protocol which lets attackers intercept and tamper with data transmitted between devices.


Vulnerable data includes contacts, keystrokes from a wireless keyboard, and the information from medical, point-of-sale, or automotive equipment etc.


The report also noted that an attacker could forge keystrokes on a Bluetooth keyboard to open a command window or malicious website.


For an attack to succeed, both paired devices must be vulnerable.


Google, Intel, and Apple have issued patches for the vulnerability. LG and Huawei have also released security fixes for certain devices.


Carnegie Mellon University’s CERT divison lists Microsoft as unaffected by the issue.


“Microsoft implements an old version of the standard, which is even less secure, rather than the broken contemporary standard,” the researchers stated.


CVE-2018-5383 was assigned to the vulnerability in the Bluetooth protocol.


CVE-2018-5383

Overview


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.

Description


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.

Impact


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.


Solution


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. Further information for vendors is provided in the Vendor Status section below.


Vendor Information