An international cybercrime gang stole $13 million from a Florida-based financial institution earlier this year, by executing a highly-coordinated heist in which thieves used ATMs around the globe to cash out stolen prepaid debit cards, KrebsOnSecurity has learned.

Jacksonville based Fidelity National Information Services Inc. (FIS) bills itself as the world’s largest processor of prepaid debit cards; FIS claims to process more than 775 million transactions annually. The company disclosed the breach in its first quarter earnings statement issued May 3, 2011. But details of the attack remained shrouded in secrecy as the FBI and forensic investigators probed one of the biggest and most complex banking heists of its kind.

FIS said it had incurred a loss of approximately $13 million related to unauthorized activities involving one client and 22 prepaid cards on its Sunrise, Fla. based eFunds Prepaid Solutions, formerly WildCard Systems Inc., which was acquired by FIS in 2007.

FIS stated: “The Company has identified that 7,170 prepaid accounts may have been at risk and that three individual cardholders’ non-public information may have been disclosed as a result of the unauthorized activities. FIS worked with the impacted clients to take appropriate action, including blocking and reissuing cards for the affected accounts. The Company has taken steps to further enhance security and continues to work with Federal law enforcement officials on this matter.” The disclosure was scarcely noted by news media.

KrebsOnSecurity recently discovered previously undisclosed details of the successful escapade. According to sources close to the investigation, cyber thieves broke into the FIS network and targeted the Sunrise platform’s “open-loop” prepaid debit cards. The balances on these prepaid cards aren’t stored on the cards themselves; rather, the card numbers correspond to records in a central database, where the balances are recorded. Some prepaid cards cannot be used once their balance has been exhausted, but the prepaid cards used in this attack can be replenished by adding funds. Prepaid cards usually limit the amounts that cardholders can withdraw from a cash machine within a 24 hour period.

Apparently, the crooks were able to drastically increase or eliminate the withdrawal limits for 22 prepaid cards that they had obtained. The fraudsters then cloned the prepaid cards, and distributed them to co-conspirators in several major cities across Europe, Russia and Ukraine.

Sources say the thieves waited until the close of business in the United States on Saturday, March 5, 2011, to launch their attack. Working into Sunday evening, conspirators in Greece, Russia, Spain, Sweden, Ukraine and the United Kingdom used the cloned cards to withdraw cash from dozens of ATMs. Armed with unauthorized access to FIS’s card platform, the crooks were able to reload the cards remotely when the cash withdrawals brought their balances close to zero.

It’s still not clear who was responsible for this attack on FIS. The company declined comment. The FBI would neither confirm nor deny that it is investigating. But the breach is eerily similar to an intricate 2008 attack against RBS WorldPay, an Atlanta-based unit of the Royal Bank of Scotland. In that heist, crooks obtained remote access to RBS’s systems and used 44 counterfeit prepaid cards to withdraw more than $9 million from at least 2,100 ATM terminals in 280 cities worldwide. The attack was so sophisticated and alarming that President Obama referred to it in a landmark cybersecurity speech.

Federal prosecutors alleged that the 2008 RBS theft was orchestrated by at least eight men from Estonia and Russia — the alleged ringleader was extradited to face charges in the United States.

Another key figure in that case was Viktor Pleschuk of St. Petersburg, Russia, who monitored the fraudulent ATM withdrawals remotely and in real-time using compromised systems within the payment card network. Pleschuk and Russian accomplice Eugene Anikin were arrested and charged in Russia. Prosecutors asked the court for five- and six-year sentences, but those requests were ignored. Pleschuk and Anikin agreed to plead guilty for their roles in the RBS heist in exchange for suspended sentences (probation, but no jail time).

Tags: eFunds Prepaid Solutions, Eugene Anikin, Fidelity National Information Services Inc., FIS, RBS Worldpay, Viktor Pleschuk, WildCard Systems Inc.