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In May 2006, nearly 12,000 malicious phishing Web sites were identified by the Anti-Phishing Working Group, a Los Altos, Calif.-based industry association focused on eliminating the scams. That's up from 3,300 sites a year earlier.

Phishing scams trick users into sending their passwords to an unintended Web site -- often unlocking access to bank accounts or other financial data.

Stanford University Department of Computer Science http://cs.stanford.edu PRODUCT: PwdHash (Password Hash) DEVELOPERS: Stanford University professor John Mitchell, associate professor Dan Boneh and students Blake Ross, Collin Jackson and Nick Miyake

But some professors and students at Stanford University are taking a big bite out of this crime with Password Hash (PwdHash), a plug-in for popular Web browsers that prevents phishing sites from getting what they want.

"Internet users often use the same password at many Web sites," says Dan Boneh, an associate professor of computer science and electrical engineering at Stanford. "A phishing attack on one site will expose their passwords at many other sites."

By simply adding "@@" to the beginning of a password when registering on a Web site, PwdHash combines the user's password with the site's domain name in an algorithm that customizes a password for the user.

If a password is stolen from a malicious site, it won't work on the authentic site "although you typed in the same password," explains professor John Mitchell, who also led the team.

Although the idea of adding a cryptographic hash function to a password isn't new, Mitchell and his team have advanced the technology by making it easy enough for end users to apply. But the project wasn't always their top priority.

Three years ago, Secret Service agents visited Stanford's engineering and computer science department to seek help in combating financial crimes. "I asked them, 'If we were to solve one problem for you, what would it be?'" Their answer: Web spoofing, now known as phishing.

Mitchell's team chose to attack the problem from the end user's point of view rather than try to persuade financial institutions to redesign their Web servers.

By the summer of 2003, they created SpoofGuard, software that detects fraudulent Web sites. In the process, developers hit on the idea of also modifying the passwords sent out from the user. And so PwdHash was born as a stand-alone piece.

The most difficult part was making PwdHash look easy. Some of the trickiest fake Web pages simply show an image or picture to indicate where to type a password instead of having "enter your password" written in text. "How would our software inside the browser know that the Web page is asking for their password? We had to know which data to apply this cryptographic hash to and which data to leave alone," Mitchell recalls.

That's when doctoral student Collin Jackson came up with the idea of adding the "@@" prefix to every password to tell the software which things are passwords and which aren't.

Today, the software is available for free, with versions for the Internet Explorer and Firefox browsers. Mitchell is trying to persuade major browser vendors to include PwdHash in upcoming releases.

"This type of technology definitely has legs," says David Jevans, chairman of the Anti-Phishing Working Group. "In the U.S., a lot of [Internet security work] is happening on the back end. But that's not going to be enough. The bad guys are always evolving."

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Collett is a Computerworld contributing writer. Contact her at stcollett@aol.com.

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