Details, Exploits of Web-Wide DNS Vulnerability Revealed

The much-discussed vulnerability in the Internet's Domain Name System is out -- and so are exploits that take advantage of it.

The flaw's founder, Dan Kaminsky of IoActive, held a Webcast today in which he gave details on his findings, and revealed that attacks have been developed to exploit it.

"Guys, we're in a lot of trouble," Kaminsky said in the Webcast. "We're still going to have the Internet, but it's not necessarily going to be the Internet we thought."

Kaminsky explained that there is a means to systematically break through the DNS hierarchy and "win the race" to guess the transaction ID of a Web query. Exploits could enable attackers to take control of Internet queries, effectively hijacking Web sessions and routing them to an unintended host.

Working with many of the industry's largest vendors, Kaminisky offered a patching technique which adds a source port randomization element to the DNS query process, which currently relies on transaction IDs alone. The source port randomization element increases the odds against hijacking from 1 in 65,000 to "one in hundreds of millions to one in multiple billions," Kaminsky says. (See Vendors Issue Massive Simultaneous Patch for Common Internet Flaw.)

Without the patch, the vulnerability could be exploited in as little as 10 seconds.

Kaminsky tried to keep the vulnerability a secret for 30 days, buying more time for vendors, users, and service providers to patch their systems. But it was only 13 days before other security researchers reverse engineered the vulnerability from the patches and made the flaw known. (See Web-Wide DNS Vulnerability Leaked.)

Kaminsky conceded that his request for secrecy was "horrible and unreasonable," but he also said that the stall tactic was effective. In fact, the percentage of vulnerable DNS servers using Kaminsky's online DNS checking tool has dropped from 86 percent on July 8-12 to 52 percent this week, he said.

The vulnerability could affect anything from a single PC to an entire country's Internet domain, Kaminsky said. "There is a possibility that this could affect clients," he said. "It's the difference between a sniper and a nuke. Neither one of them is good, but as you're prioritizing, you've got to worry about the nuke first."

Other researchers said the threat from the new exploits is real and serious. "If your CEO gives you a hard time about spending time and money to do these patches, let him know that the next time he goes to MLB.com to get the baseball scores, that might not be what he's going to get," said Rich Mogull, founder and principal analyst at Securosis.

Kaminsky will go into further depth on the vulnerability and the methods for handling it when he makes a presentation at the Black Hat conference on Aug. 6.

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