In tests, the researchers were able to do things like change firmware and redirect a D-Link Systems DI-524 wireless router to look up Web sites from a DNS (Domain Name System) server of their choosing. They describe these attacks in a paper, authored by Sid Stamm and Markus Jakobsson of Indiana University, and Symantec's Zulfikar Ramzan.
"By visiting a malicious Web page, a person can inadvertently open up his router for attack," the researchers write. "A Web site can attack home routers from the inside and mount sophisticated... attacks that may result in denial of service, malware infection, or identity theft."
Once the router has been compromised, victims can be redirected to fraudulent Web sites, the researchers say. So instead of downloading legitimate Microsoft software updates, for example, they could be tricked into downloading malware. Instead of online banking, they could be giving up sensitive information to phishers.
At the heart of the problem is the fact that consumer routers ship with simple, well-known default passwords, like "admin," which could be exploited by attackers.
The researchers blame router makers for shipping products with "poorly secure default settings."
Vendors like D-Link and Cisco Systems are aware of the problem. "It's a concern to us," said Karen Sohl, a spokeswoman with Cisco's Linksys group. "We've shipped about 30 million routers and we want those 30 million customers to understand why it's so important to change [the default password]."
Both Cisco and D-Link said they've taken steps to avoid this type of security problem. Over the past few years they've introduced step-by-step "wizard" software to configure their routers, and these products always suggest that the user come up with a unique password.
The problem is that the routers still work if the password is left as default. And that's not likely to change anytime soon, according to Michael Scott, D-Link's technical media manager.
Users wouldn't buy routers that forced them to enter unique passwords, he said. "That would only result in returned products, and then they would buy one of our competitors products," he said.