Hacker intrusions into bank Web sites are relatively rare, according to the FDIC. But the risk is there, warns Atul Prakash, a University of Michigan computer science professor who studied 214 sites. His 2006 survey, presented at the July 25 Symposium on Usable Privacy & Security, found 75% of sites vulnerable to hacking, with two big worrisome trends: log-in boxes placed on insecure pages on a bank’s domain and the use of third-party vendors that transfer customers to insecure outside pages (via, say, a “Contact Us” link). “Banks should try to keep the site on a single domain,” Prakash says, adding that users should look for a url starting with “https” on pages asking for sensitive personal data. The “s” signals an extra security layer.