ING Direct Bank, an online bank with 6.5 million customer accounts, Wednesday announced it's offering free antiphishing software to its customers.

The Windows-based software, called Rapport and developed by Trusteer, detects when a user is going to a phishing site and presents that information in a pop-up window so that the user can decide whether or not to continue, says Rob Weaver, head of IT security for the Web-based bank, which also operates banking "cafes" with kiosks in six U.S. cities.

Phishing, in which attackers attempt to lure victims into using fraudulent Web sites in order to steal their personal data, is a "huge problem," Weaver says. To combat it, ING Direct Bank is subsidizing the Trusteer software, which retails for $20, for its customers. New York brokerage firm Muriel Siebert & Co. has also chosen to offer Rapport to its customers, according to Trusteer.

The Trusteer Rapport desktop software monitors the users' behavior on the computer to check for signs that they may be attempting to use a fraudulent Web site mimicking the real ING Direct. The software also watches for keyloggers that might steal data. The Rapport software from ING also lets users select two other Web sites in addition to ING's to monitor.

Unlike antivirus software, the role of the Trusteer software is not to eradicate malicious code on compromised desktops but to warn about phishing attacks and keyloggers. "It protects sensitive fields against keystroke logging and browser hijacking," Weaver says.

After it obtains experience with customer adoption of the antiphishing software, ING Direct Bank may take the step of factoring in use of it into its risk-based anti-fraud monitoring system since the software is expected to lower security risk.