CVE-2017-14937: Use of a Broken or Risky Cryptographic Algorithm

The airbag detonation algorithm allows injury to passenger-car occupants via predictable Security Access (SA) data to the internal CAN bus (or the OBD connector). This affects the airbag control units (aka pyrotechnical control units or PCUs) of unspecified passenger vehicles manufactured in 2014 or later, when the ignition is on and the speed is less than 6 km/h. Specifically, there are only 256 possible key pairs, and authentication attempts have no rate limit. In addition, at least one manufacturer's interpretation of the ISO 26021 standard is that it must be possible to calculate the key directly (i.e., the other 255 key pairs must not be used). Exploitation would typically involve an attacker who has already gained access to the CAN bus, and sends a crafted Unified Diagnostic Service (UDS) message to detonate the pyrotechnical charges, resulting in the same passenger-injury risks as in any airbag deployment.