Researchers from Quarkslab have uncovered a severe security flaw in millions of RFID cards manufactured by Shanghai Fudan Microelectronics, revealing a hardware backdoor that enables instant cloning of these contactless cards. The vulnerability affects the FM11RF08S variant of the MIFARE Classic cards, which were promoted as secure against known card-only attacks due to their “static encrypted nonce” feature. However, the backdoor discovered by the researchers allows any entity with knowledge of it to bypass user-defined security keys and access all data on the cards within minutes.
The research highlights that the FM11RF08S cards are susceptible to cloning because the backdoor key is consistent across all units, regardless of the key diversification intended to enhance security. The researchers were able to crack the sector keys by exploiting the reuse of keys across at least three sectors or cards. This critical flaw means that attackers can read all user data blocks, including those protected by access rights, making it a significant security risk for users of these RFID systems.
Quarkslab’s investigation also revealed that this vulnerability is not isolated to the FM11RF08S cards. A similar backdoor was found in earlier generations of Fudan cards, which were also protected by a different key that was subsequently cracked. This pattern of vulnerabilities extends to other RFID card models from Fudan and even older cards from manufacturers such as NXP and Infineon. The discovery underscores a troubling trend in RFID technology security, with backdoors persisting across multiple generations of products.
In light of these findings, Quarkslab is urging all organizations using MIFARE Classic cards to evaluate their security infrastructure and assess the potential risks posed by these vulnerabilities. The affected cards are not limited to the Chinese market; they have been found in various locations worldwide, including hotels in the U.S., Europe, and India. Prompt action is necessary to mitigate the security risks associated with these compromised RFID systems and protect sensitive information from unauthorized access.
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