Online Banking: Widespread Security Flaws Revealed

Online bankers, beware. More than 75 percent of bank Web sites surveyed by a research team had at least one design flaw that could make customers vulnerable to cyber thieves.

University of Michigan computer scientist Atul Prakash and his graduate students Laura Falk and Kevin Borders examined the Web sites of 214 financial institutions in 2006 and found design flaws that, unlike bugs, cannot be fixed with a patch.

The security holes stem from the flow and the layout of these Web sites, according to their study. The flaws include placing log-in boxes and contact information on insecure Web pages as well as failing to keep users on the site they initially visited. Prakash said some banks may have taken steps to resolve these problems since this data was gathered, but overall he still sees much need for improvement.

"To our surprise, design flaws that could compromise security were widespread and included some of the largest banks in the country," Prakash said. "Our focus was on users who try to be careful, but unfortunately some bank sites make it hard for customers to make the right security decisions when doing online banking."

Computer intrusion rising

About 40 percent of Americans use the Internet for banking, according to a February 2008 survey conducted by Pew Internet. In 2011, 76 percent of online households will bank online, according to Forrester Research.

The flaws leave cracks in security that hackers could exploit to gain access to private information and accounts. The FDIC says computer intrusion, while relatively rare compared with financial crimes like mortgage fraud and check fraud, is a growing problem for banks and their customers.

A recent FDIC Technology Incident Report, compiled from suspicious activity reports banks file quarterly, lists 536 cases of computer intrusion, with an average loss per incident of $30,000. That adds up to nearly $16 million in losses in the second quarter of 2007. There were two and a half times more computer intrusions in the second quarter of 2007 compared to the first quarter. In 80 percent of the cases, the source of the intrusion is unknown but it occurred during online banking, the report states.

Look for 'https' and other tips

The design flaws Prakash and his team looked for are:

  • -Placing secure login boxes on insecure pages: A full 47 percent of banks were guilty of this. A hacker could reroute data entered in the boxes or create a spoof copy of the page to harvest information. In a wireless situation, it's possible to conduct this man-in-the-middle attack without changing the bank URL for the user, so even a vigilant customer could fall victim. To solve this problem, banks should use the standard "secure socket layer" (SSL) protocol on pages that ask for sensitive information, Prakash says. (The urls for SSL-protected pages begin with https rather than http.) Most banks use SSL technology for some of their pages, but only a minority secure all pages this way.
  • -Putting contact information and security advice on insecure pages: At 55 percent, this was the flaw with the most offenders. An attacker could change an address or phone number and set up his own call center to gather private data from customers who need help.
  • -Having a breach in the chain of trust: When the bank redirects customers to a site outside the bank's domain for certain transactions without warning, it has failed to maintain a context for good security decisions, Prakash says. He found this problem in 30 percent of the banks surveyed. The solution, Prakash says, is to warn users they'll be moving off the bank's site to a trusted new site. Or the bank could house all of its pages on the same server. This problem often arises when banks outsource some security functions.
  • -Allowing inadequate user IDs and passwords: Researchers looked for sites that use social security numbers or e-mail addresses as user ids. While this information is easy for customers to remember, it's also easy to guess or find out. Researchers also looked for sites that didn't state a policy on passwords or that allowed weak passwords. Twenty-eight percent of sites surveyed had one of these flaws.
  • -E-mailing security-sensitive information insecurely: The e-mail data path is generally not secure, Prakash says, yet 31 percent of bank Web sites had this flaw. These banks offered to e-mail passwords or statements. In the case of statements, users often weren't told whether they would receive a link, the actual statement, or a notification that the statement was available. A notification isn't a problem, but e-mailing a password, a link or a statement, isn't a good idea, Prakash says.

Prakash, who received no special funding for this research, initiated the study after noticing flaws on his own financial institutions' Web sites. He and his colleagues will present their findings July 25 at the Symposium on Usable Privacy and Security meeting at Carnegie Mellon University in Pittsburgh.

A list of the banks surveyed can be found here.