Drive-by Pharming Attacks Potential Threat to Broadband Users

Researchers reveal malicious code that could be used to target routers.

Researchers at Symantec and the Indiana University School of Informatics have uncovered a new threat to broadband users.

The attack, nicknamed "Drive-by Pharming", uses JavaScript on a Web site created by a hacker to reconfigure broadband routers. Once the user clicks on a link, the malicious JavaScript code changes the DNS settings on the users router so that every time the user logs on to a Web site, DNS resolution will be performed by the attacker.

As a result, the attacker has complete control over which Web sites the victim visits on the Internet. A user may think, for example, that they are visiting their online banking Web site, but in reality they have been redirected to a phony site set up by the attacker.

"Its actually a very simple technique," said Zulfikar Ramzan, senior principal researcher at Symantec Security Response, in an interview with eWEEK. In fact, he said, the malicious code is, at its core, just one line.

The code simulates a log-in to change the password on the router, Ramzan explained. To prevent this type of attack, users need only change their router password during installation, he said.

Many users, however, do not change their default password issued by the router manufacturer, Ramzan said. According to a separate informal study conducted by Indiana University, up to 50 percent of home broadband users are susceptible to this attack. The manufacturers could help by issuing unique passwords for each router based on product serial numbers, he said.

However, Ramzan and Professor Markus Jakobsson of the Indiana University School of Informatics said users are their own best line of defense.

/zimages/3/28571.gifSpying on users: getting to the rootkit of the matter. Click here to read more.

"While drive-by pharming arises due to inadequate protective measures, there is also another human component: If an attacker can trick you into visiting his page, he can probe your machine," Jakobsson said in a statement. "Deceit is not new to humankind, but it is fairly recently that security researchers started taking it seriously."

For now though, the attack lives only in the realm of the theoretical—there have been no real world examples of the attack being launched, Ramzan said.

However, due to its simplicity and the number of people who could be affected, researchers thought it best to warn the public, he said.

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