CVE-2019-9506: Blutooth BR/EDR specification does not specify sufficient encryption key length and allows an attacker to influence key length negotiation

Bluetooth. An input validation issue existed in Bluetooth. This issue was addressed with improved input validation.

The Bluetooth BR/EDR encryption key negotiation protocol is vulnerable to packet injection that could allow an unauthenticated user to decrease the size of the entropy of the encryption key, potentially causing information disclosure and/or escalation of privileges via adjacent access. There is not currently any knowledge of this being exploited.

Note:

Not all bluetooth devices are vulnerable to this flaw. Only devices that can connect to another using BR/EDR encryption negotiation protocol.

CERT notification: https://kb.cert.org/vuls/id/918987/

Upstream patches: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=d5bb334a8e171b262e48f378bd2096c0ea458265 https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=693cd8ce3f882524a5d06f7800dd8492411877b3 https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=eca94432934fe5f141d084f2e36ee2c0e614cc04

Branded site: https://knobattack.com/

— Red Hat

The Bluetooth BR/EDR specification up to and including version 5.1 permits sufficiently low encryption key length and does not prevent an attacker from influencing the key length negotiation. This allows practical brute-force attacks (aka "KNOB") that can decrypt traffic and inject arbitrary ciphertext without the victim noticing.