My bank makes it easy to check account balances, pay bills and transfer money using a smart phone. And I do all those things, although I'm not sure I should.

My doubts only deepened after I talked with Avivah Litan, a security expert at consulting firm Gartner Research. Banks are still feeling their way when dealing with mobile technology, she told me.

"A lot of banks are working out what their security guidelines should be and what they should allow," Litan said.

In their eagerness to keep up with new technologies, banks sometimes stumble. That became apparent late last year, when several major banks, including Wells Fargo, Bank of America and USAA, had to rush to fix flaws in their iPhone and Android apps. Research company viaForensics found that the programs were storing sensitive information, such as user names and passwords -- sometimes in plain text. Although the banks said no one's information had actually been stolen, the data could have been easy pickings for thieves.

The situation with mobile banking is somewhat analogous to that of debit card fraud about a decade ago -- security procedures haven't yet caught up with the risks. After credit card fraud spiked in the 1990s, banks invested in software and other tools to sniff out potentially bogus transactions, which led to dramatic declines in such fraud. But crooks then switched to easier targets: debit cards. It took banks a while to ramp up technology for thwarting the bad guys.

Similarly, banks are quite good at detecting non-mobile online fraud. For instance, when you log on to your bank's website from your home computer, the bank's software makes sure it recognizes the machine being used. It also checks that your transaction fits in with your normal banking patterns -- and raises a red flag at unusual activity. The technology for authenticating mobile banking requests isn't as robust, Litan said.

In fact, Litan said, we users should be concerned if our bank allows us to do too much with our cell phones right now. High-risk transactions -- such as adding a new payee to our bill payment system or transferring money to a new outside account -- may be more than our banks' security systems can handle.

Security concerns won't keep mobile banking from growing, of course. Just over 13% of U.S. households accessed their bank accounts from a mobile device in the fourth quarter of 2010, up from 11.6% in the first quarter, according to ratings firm Nielsen.

One in five American adults will use mobile banking services by 2015, predicts Forrester Research.