DNS problem linked to DDoS attacks gets worse

By Robert McMillan
IDG News Service
November 13, 2009

Internet security experts say that misconfigured DSL and cable modems are worsening a well-known problem with the Internet's DNS (domain name system), making it easier for hackers to launch distributed denial-of-service (DDoS) attacks against their victims.

According to research set to be released in the next few days, part of the problem is blamed on the growing number of consumer devices on the Internet that are configured to accept DNS queries from anywhere, what networking experts call an "open recursive" or "open resolver" system.
As more consumers demand broadband Internet, service providers are rolling out modems configured this way to their customers said Cricket Liu, vice president of architecture with Infoblox, the DNS appliance company that sponsored the research. "The two leading culprits we found were Telefonica and France Telecom," he said.

In fact, the percentage of DNS systems on the Internet that are configured this way has jumped from around 50% in 2007, to nearly 80% this year, according to Liu.

Though he hasn't seen the Infoblox data, Georgia Tech Researcher David Dagon agreed that open recursive systems are on the rise, in part because of "the increase in home network appliances that allow multiple computers on the Internet."