Android 6.0 has an authentication bypass for attackers with root and physical access

Android 6.0 has an authentication bypass for attackers with root and physical access. Cryptographic authentication tokens (AuthTokens) used by the Trusted Execution Environment (TEE) are protected by a weak challenge. This allows adversaries to replay previously captured responses and use the TEE without authenticating. All apps using authentication-gated cryptography are vulnerable to this attack, which was confirmed on the LG Nexus 5X.