We describe in this paper how to perform a padding oracle attack against the GlobalPlatform SCP02 protocol. SCP02 is implemented in smart cards and used by transport companies, in the banking world and by mobile network operators (UICC/SIM cards). The attack allows an adversary to efficiently retrieve plaintext bytes from an encrypted data field. We provide results of our experiments done with 10 smart cards from six different card manufacturers, and show that, in our experimental setting, the attack is fully practical. Given that billions SIM cards are produced every year, the number of affected cards, although difficult to estimate, is potentially high. To the best of our knowledge, this is the first successful attack against SCP02.