Banks are naturally alarmed over those trends. "Trust is really the fundamental foundation for the banking relationship, so maintaining customer trust is critical," says Rob Rowe, regulatory counsel for Independent Community Bankers of America.

Banks can take solace, however, in separate surveys showing that customers are willing to bank online if security is tightened. A study by Entrust Inc. found that 72% of those who do not currently bank online will participate if identity security is improved and that 90% of those who already bank online would do so more often if their identities were better protected. Consumers also say they don't mind going through additional security steps if that will ensure their information doesn't fall into the wrong hands.

So what are banks doing? Many plan to add steps to customer log-in procedures. Banks will begin requiring more than just a password for online access. Some may start providing customers with keychain-size "tokens" that display new passwords every 60 seconds. Individuals logging into their accounts would have to use their standard password plus whatever passcode the token was flashing at that instant. Such measures will make it impossible for thieves to access a consumer's account simply by stealing his or her password.

Bank of America has a new program to assure customers that they are at a legitimate Bank of America site. If a customer registers a specific computer for access to an online account, when the customer logs on from that computer, a predetermined, preset image is displayed to show that the site is legitimate.

To build consumer confidence, banks will highlight their new security steps in their marketing campaigns.

Customers aren't likely to see any rise in costs as a result of enhanced security measures. Banks understand that customers expect their financial providers to take care of their data and know that security demands are simply part of the cost of doing business. "Increasing security is an investment for banks or anyone doing business online," says Charlotte Birch of the American Bankers Association. "It's a way to bring in business."

Another problem banks face is consumers' growing unwillingness to trust online communications, even those that truly are from their financial services provider. Forrester's survey found that 20% of consumers no longer open e-mails that say they are from their financial provider because of fears of online fraud.

Banks and customers both lose in that situation. It's a problem for banks that want to use e-mail to communicate with customers more cost effectively, and customers lose out on the ease and speed of getting information via the Internet. Expect banks to come up with ways to assure customers that the communications they're receiving are legitimate, as Citibank recently started doing by providing the customer's last name and last four digits of the customer's account number in e-mails from the company.