APDU-Level Attacks in PKCS#11 Devices

In this paper we describe attacks on PKCS#11 devices that we successfully mounted by interacting with the low-level APDU protocol, used to communicate with the device. They exploit proprietary implementation weaknesses which allow attackers to bypass the security enforced at the PKCS#11 level. Some of the attacks leak, as cleartext, sensitive cryptographic keys in devices that were previously considered secure. We present a new threat model for the PKCS#11 middleware and we discuss the new attacks with respect to various attackers and application configurations. All the attacks presented in this paper have been timely reported to manufacturers following a responsible disclosure process.