Security measures such as one-time passwords and phone-based user authentication, considered among the most robust forms of security, are no longer enough to protect online banking transactions against fraud, a new report from research firm Gartner Inc. warns.

Increasingly, such measures are overwhelmed by online criminals looking to pillage bank accounts using valid login credentials stolen from customers, the report said.

Going forward, banks need to quickly implement additional layers of security to protect their customers from falling victim to online fraud, said Avivah Litan, Gartner analyst and the report's author.

Gartner's warning comes amid a sharp uptick in fraud involving the exploitation of valid online banking credentials. In August, NACHA- the Electronics Payments Association issued an alert , warning members about attacks involving the theft of online banking credentials, such as usernames and passwords mostly from small- and medium-size businesses. Cybercriminals used the stolen credentials to take over corporate accounts and initiate unauthorized transfers of funds via electronic payment networks, NACHA said in its warning. NACHA, with more than 11,000 financial institutions as members, oversees the Automated Clearing House (ACH) electronic payments network.

Just a few days earlier, a similar alert was sent to members of the Financial Services Information Sharing and Analysis Center. The alert identified organized cybercrime groups in Eastern Europe as predominantly responsible for illegally siphoning millions of dollars off corporate accounts and sending the money overseas via popular money and wire transfer services.

Last month, the FBI's ">Internet Crime Complaint Center noted that as of October, cybercrooks had attempted to steal approximately $100 million from U.S. banks using stolen log-in credentials. On average, the FBI is seeing several new cases opened each week, the complaint center said. In most instances, the crooks used sophisticated keystroke logging Trojan horse programs to steal login credentials from company employees authorized to initiate funds transfers on behalf of the business, the FBI noted.

According to Litan, several Gartner banking clients have reported being victimized or targeted by attacks involving the use of malicious code hidden in Web browsers to intercept and corrupt banking transactions.

In some cases, the Trojan program lurks in the user's browser and is activated when the user logs into a banking site. The malware copies the user's ID, password and one-time password and immediately uses them to transfer funds, while the victim gets an error message on the computer screen. In other cases, a Trojan program might intercept a transaction that is taking place between a bank and a customer, and change the transaction without either the user or the bank knowing what is going on, she said.

For instance, a request to transfer a certain amount of money from one account to another could be modified so that the request the bank gets would be different from the request sent by the user. However, when the bank asks the customer to confirm the transaction, the details of the transaction would appear to the user to be the same as the one he had requested, Litan said. "The malware is changing what the user sees. So even if you put in a one-time password, you are confirming the wrong transaction," she said.

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