Attacks on Java Card 3.0 Combining Fault and Logical Attacks

Java Cards have been threatened so far by attacks using ill-formed applications which assume that the application bytecode is not verified. This assumption remained realistic as long as the bytecode verifier was commonly executed off-card and could thus be bypassed. Nevertheless it can no longer be applied to the Java Card 3 Connected Edition context where the bytecode verification is necessarily performed on-card. Therefore Java Card 3 Connected Edition seems to be immune against this kind of attacks. In this paper, we demonstrate that running ill-formed application does not necessarily mean loading and installing ill-formed application. For that purpose, we introduce a brand new kind of attack which combines fault injection and logical tampering. By these means, we describe two case studies taking place in the new Java Card 3 context. The first one shows how ill-formed applications can still be introduced and executed despite the on-card bytecode verifier. The second example leads to the modification of any method already installed on the card into any malicious bytecode. Finally we successfully mount these attacks on a recent device, emphasizing the necessity of taking into account these new threats when implementing Java Card 3 features.