Using a cellphone to check balances, transfer money and pay bills is still a novelty for many, particularly those who are older and still getting used to the idea of banking online.

For example, baby boomer Harlan Platt, professor of finance at Northeastern University in Boston who often speaks on mobile banking, says he's not ready to risk having his bank account hacked for the convenience of checking his balance remotely.

"Most of people's banking activity can be conducted at home, at night, on a safe network," he says.

Still, Bissell says that while the older demographic is slower to adapt to new technology, they usually catch up with the mainstream within two years, according to PA Consulting's research. And the security risks, while a reality, have been addressed by banks.

"Banks have hacking and antifraud controls in place," Bissell says. "Access to (customer) accounts from mobile devices is just as secure as online." In case a hacker does get into the system, many banks cover losses, with no minimum liability required of the customer.