The vulnerability in CasfID Servicios Tecnológicos NFC wristbands arises from the use of an insecure cryptographic algorithm in the authentication process of MIFARE Classic-based cards (FM11RF08S). This weakness enables attackers to perform a Backdoored Nested Attack to extract access keys, fully read the wristband contents, and clone the credentials onto rewritable cards. Exploitation can lead to impersonation of attendees and unauthorized use of stored balances in the cashless payment system. The issue affects the version used at Resurrection Fest 2025. No vendor-provided patch or remediation level is indicated, and no known exploits are reported in the wild.

Successful exploitation allows attackers to retrieve cryptographic keys, read all data on the wristbands, and clone them. This leads to impersonation of legitimate users and fraudulent use of their stored balances, resulting in financial losses for both users and event organizers. The vulnerability compromises the integrity and confidentiality of the cashless payment system.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, users and event organizers should be aware of the risk of cloning and unauthorized use. Consider additional verification methods or alternative technologies for secure transactions. Monitor vendor communications for updates on remediation.