Web browser attack skirts corporate firewall

Dan Kaminsky, director of penetration testing for IO Active, showed how problems in the way browser software works with the Internet's domain name system (DNS) could be exploited to give attackers access to any resources behind the corporate firewall.

He described a multistep attack that could be used to scan corporate networks for data or vulnerabilities. But at the heart of the attack is a 1996 paper by Princeton researchers showing how a Java applet could be used to access systems on a victim's network. "It's one of the few things that's actually come back from the dead," Kaminsky said.

The fundamental problem, according to Kaminsky, is in the way that Web browser software decides how to trust other computers. This decision is based on the Internet domain name of the computer, and that DNS (Domain Name System) information can be misused, Kaminsky said. "It's a binding problem," he said during an interview after his talk. "They assume a value is not changing, but the attacker can change it whenever he chooses."