New warnings about cybercriminal attacks on ATMs and card systems have been issued recently. Portals and Rails looks again at this type of cyberattack, which the Secret Service calls “unlimited operation” because it resets account balances and removes ATM withdrawal limits.

The Federal Financial Institutions Examination Council (FFIEC) issued a warning in April to financial institutions about criminals continuing to launch attacks against ATM and web-based card management systems, especially those of small- to medium-size financial institutions (FI). Dubbed “unlimited operation” by the U. S. Secret Service, this type of attack can saddle a financial institution with fraud losses in the millions of dollars. As we highlighted in a postfrom last May, a bank in Oman experienced this type of attack in late 2012, which resulted in a loss to the bank of almost $40 million. Imagine the impact of a loss of that magnitude to a small to midsized FI.

These attacks are especially concerning for a number of reasons. First, the criminal organizations that carry them out are highly sophisticated and well-organized, and they have an international reach. The Oman attack included a money mule network across 26 countries—including the United States—performing more than 36,000 withdrawals in a 12-hour period.

Second, unlike typical counterfeit card fraud attacks that involve a large number of accounts, the criminals behind the card management system frauds need to compromise only a small number of card accounts. The attack that resulted in the $40 million loss involved only 12 accounts. Early in this type of operation, the criminals generally obtain the PINs of the cards for these accounts by conducting some sort of covert surveillance (pinhole camera or shoulder surfing). They then counterfeit the cards using those PINs.

Third, the attacks are generally timed to take place around holidays, when bank, IT, and fraud monitoring staff levels are low.

Fourth, the criminals get remote access to the financial institutions’ card management systems to reset account balances and card withdrawal parameters. They can then use the counterfeit cards over their pre-established transaction limits or balances and drain the ATMs of all cash. The criminals usually obtain access to FIs’ networks using e-mail phishing schemes that target processor or network employees. Through gullible employees, malware is loaded onto the network that later gives the criminals access to the FIs’ card management systems.

Major online networks now have transaction velocity monitoring capability, which detects a high number of transactions on an individual account. This approach is necessarily only a secondary and reactive measure, not a preventive measure.

FIs should immediately address the risk mitigation steps that the new FFIEC warning outlines. Because the vast majority of small to midsized FIs depend on third-party processors to run their card management systems, it is imperative all FIs verify that their processors have the controls and safeguards in place to prevent such attacks, and they should insist on seeing validation of those controls.