Demo neuters antiphishing measure

In the unlikely event readers needed another reason to doubt the efficacy of the sitekeys that Bank of America, Yahoo! and others claim make their sites more secure, a muck-raking hacker has demonstrated a simple means of thwarting the measure.

The demo comes courtesy of Christopher Soghoian, the Indiana University graduate student whose online generator for spoofed airline boarding passes attracted considerable attention from the FBI.

Sitekeys, which financial institutions have embraced as a way of thwarting phishing attacks, allow customers to select an easily recognizable image that is displayed on login pages. A page that asks for password but doesn't show the image can immediately be pegged as a forgery. Or so the thinking goes.

When a BofA user, for example, accesses an account using a computer that's never before visited the site, the online ID and account location are the only pieces of information that are requested. When those fields are entered, BofA responds with a preset security question, such as, "What was the city of your high school?" Only after the question is answered correctly is the visitor taken to a page bearing the image, or sitekey, and a prompt to enter an account password.

Soghoian shows how a 130-line ruby script can largely neuter the protective measure by employing a classic man-in-the-middle technique. In the demo, a spoofed Bank of America page prompts the visitor for the online ID and state and then transmits them to the real BofA site. When BofA responds with the security question, the phishing site relays it to the visitor and then sends the answer back to the bank. Before you know it, BofA has provided the phisher with the user's sitekey which is then affixed to the spoofed page requesting the password.

"Just because you see your Sitekey/Passmark image, or Yahoo personalized sign-in seal, you should still be careful," Soghoian writes. "Those security schemes, alone, are not enough to protect your security online." The sage advice is at odds with BofA's claims that "when you see your SiteKey, you can be certain you're at the valid Online Banking website at Bank of America, and not a fraudulent look-alike site."

It isn't the first time sitekeys have been revealed to be a flawed means of protecting accounts. A recent study found that 92 percent of participants entered account passwords even when the required sitekey was missing. Other research has called into question the usefulness of personalized greetings that eBay users can deploy. ®