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News > February 2008


DNS Inventor Warns of the Next Big Threat

The inventor of DNS (Paul Mockapetris) says that the industry is just one multi million dollar corporate data breach away from a serious threat of corrupted DNS resolution servers

The chief scientist and chairman of the network and naming address vendor Nominum (Paul Mockapetris) says the recent research conducted on corrupt DNS resolution servers at Georgia tech and Google illustrates another way hackers are attacking DNS to infect users. The new threat dubbed “DNS resolution path corruption” is where malicious DNS servers provide false data in order to send users to malicious sites.

The results of the DNS resolution research found that of the around 17 million open-recursive DNS servers on the net about 4 % (or 68,000) are performing malicious operations by answering the DNS queries with false data and being sent to malicious sites. “This report demonstrates that people are getting lured out to dark alleyways of the Internet. The actual damage isn’t documented here, but it will be” somewhere when someone loses the first $10 million to $100 million to this type of attack, Mockapetris says.

This increasing used method of attack forces users to rely on rogue domain name servers, which results what is known as a “second secret authority” on the Internet. Dozens of viruses were found that infected DNS resolution paths and that hundreds of URLs each week do drive by alterations of hosts DNS settings.

OpenDNS has legitimate reasons for redirecting or editing a DNS entry/registry that block unwanted sites and correct user errors and prevent users being sent to typo squatters sites. “. But users need to be aware that the bad guys have also figured out how to abuse DNS this way, Mockapetris says.”

The Georgia Tech and Google researchers focused on the malicious alteration of DNS answers in their study. “Companies are rewriting DNS answers, ideally to improve the user experience, but also to expose the users to ads,” says Georgia Tech’s Dagon. “There are also some laudable security improvements that come from rewriting answers. For example, OpenDNS can protect users from malicious sites. But DNS vendors aren't the only ones commercialising the alteration of DNS traffic. Malware authors also use this technique to exploit victims.”

Nominum’s Mockapetris says combating this threat may require revisiting the DNS “food chain” -- meaning “data from the user who owns the domains, to the user who wants to access it, and who gets to modify it,” he says. “The fewer places [it gets modified], the better.” The researchers focused on incorrect and malicious answers provided by DNS machines, Dagon says. “The... alteration of DNS answers deserves further study. In service of that goal, we will make data from the ongoing study available to the research and DNS communities,” he says.