Cardsystems Solutions in 2005
Cardsystems Solutions200540,000,000FinancialHacked3. Credit card informationhttp://www.msnbc.msn.com/id/8260050/ns/technology_and_science-security/t/million-credit-cards-exposed/#.UFiz7aRYtmgMSNBCThird-party payment processor for Visa, Mastercard, Amex, and Discover. CardSystems was fingered by MasterCard after it spotted fraud on credit card accounts and found a common thread, tracing it back to CardSystems. An unauthorized entity put a specific code into CardSystems' network, enabling the person or group to gain access to the data. It's not clear how many of the 40 million accounts were actually stolen.