If you haven't changed the default password on your home router, do so now.

That's what researchers at Symantec Corp. and Indiana University are saying, after publishing the results of tests that show how attackers could take over your home router using malicious JavaScript code.

For the attack to work, the bad guys would need a couple of things to go their way. First, the victim would have to visit a malicious Web site that served up the JavaScript. Second, the victim's router would have to still use the default password that it's pre-configured with it out of the box.

In tests, the researchers were able to do things like change firmware and redirect a D-Link Systems Inc. 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 Corp. 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.

"Owners of home routers who set a moderately secure password -- one that is non-default and non-trivial to guess -- are immune to router manipulation via JavaScript," the paper states.

The researchers blame router makers for shipping products with "poorly secure default settings."

Vendors like D-Link and Cisco Systems Inc. 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]."

The IDG News Service is a Network World affiliate.