Attackers could change the configuration of home routers using JavaScript code, security researchers at Indiana University and Symantec have discovered. The researchers first published their work in December, but Symantec publicized the findings on Thursday.
The researchers found that it is possible to change the DNS, or Domain Name System, settings of a router if the owner uses a connected PC to view a Web page with the JavaScript code. This DNS change lets the attacker divert all the Net traffic going through the router. For example, if the victim types in "www.mybank.com," the request could be sent to a similar-looking fake page created to steal sensitive data.
"I have been able to get this to work on Linksys, D-Link and Netgear routers," Symantec researcher Zulfikar Ramzan said. "You can create one Web site that is able to attack all routers. My feeling is that it is just a matter of time before phishers start using this."
After a router's DNS setting is changed, all computers connected to the device will use the DNS server set up by the attacker to find their way on the Internet. DNS functions like the phonebook of the Internet, mapping text-based addresses such as www.news.com to actual numeric Internet Protocol addresses of a Web site.
The attack works on any type of home router, but only if the default router password hasn't been changed, Ramzan said. The malicious JavaScript code embedded on the attacker's Web page logs into the router using the default credentials--often as simple as "admin" and "password"--and changes the settings.
"One of the issues is that the set-up steps in the router don't prompt you to change the password," Ramzan said. As a result, many people never properly configure their networking gear, he said.
In crafting their proof-of-concept attack code, Ramzan and researchers at Indiana University built upon earlier research that showed how JavaScript could be used for malicious purposes. Jeremiah Grossman, chief technology officer at WhiteHat Security, demonstrated how JavaScript let outside attackers target internal corporate networks.
Grossman is impressed by the Symantec and Indiana University work. "This is very dangerous stuff and could be highly effective if used in the wild," he said.
Router makers already know of the problems with default passwords as well as other security concerns, they said. Linksys, for example, recommends that customers change the default password during the installation procedure, said Karen Sohl, a representative for the company, a division of Cisco Systems. "We are aware of this," she said.
On its Web site, Linksys warns users that miscreants are taking advantage of the default passwords. "Hackers know these defaults and will try them to access your wireless device and change your network settings. To thwart any unauthorized changes, customize the device's password so it will be hard to guess," the company states.
Still, although Linksys' software recommends the password change, consumers can either plug in their router without running the installation disk or bypass the change screen, keeping the defaults. The company offers detailed information on how to change the router password on its Web site. Netgear and D-Link also recommend password changes.
