Cracking MIFARE Classic 1K RFID

This report analyzes weaknesses in Mifare Classic 1K RFID cards, describes step‑by‑step exploitation using a Proxmark3 (including Dark‑Side, Nested, and mfkey64 attacks), and presents a case study showing that MBTA Charlie Cards used the same static keys across cards—allowing full read/write access and potential cloning or fraudulent value modification—while recommending mitigations such as per‑card dynamic keys, centralized value storage, or upgrading cards.