DNS remains vulnerable one year after Kaminsky bug

Cache poisoning attacks rise amid scramble to patch DNS servers, deploy security add-on

In the meantime, ISPs and Web site operators are seeing a growing number of cache poisoning attacks, although few of them are publicly disclosed.

On July 17, Irish ISP Eircom reported that it was a victim of a cache poisoning attack, which resulted in two major outages and customers being re-directed from popular Web sites such as Facebook to bogus Web sites.

In April, Brazilian bank Bradesco confirmed that some of its customers were redirected to Web sites that tried to steal their passwords because its ISP, Net Virtua, was the victim of a cache poisoning attack.

``We see evidence of cache poisoning attacks because we monitor open recursive servers, and we see it occurring on an ongoing basis,’’ Joffe said. ``A year ago, it was a theoretical threat. Today, it's occurring.’’

The risk of cache poisoning attacks is actually greater than it was a year ago because the Kaminsky flaw is well known in the hacking community.

"The incidence of cache poisoning attacks on the rise, and people are scared because they’re insidious little beasts," Gersch says, pointing out that companies often don't realize they are victims of a cache poisoning attack. "We want to get to DNSSEC, but the industry is working on creative methods to work around the problem until DNSSEC is deployed."

Significant progress has been made in DNSSEC deployment in the last year.

The U.S. federal government mandated that DNSSEC be deployed across its .gov domain by the end of 2009, and it is taking steps to ensure that the DNS root servers are signed during the same time frame. By June 2010, federal agencies will be required to deploy DNSSEC on their internally facing DNS servers, too.

"Around 70 delegations under .gov are signed," Rose said, pointing out that www.nist.gov is one of the early adopters of DNSSEC.

The .org domain supports DNSSEC, as does country code top-level domains operated by Sweden, Brazil, Puerto Rico, Bulgaria and the Czech Republic. Most significant is VeriSign’s plan to deploy DNSSEC on .com and .net, which it says will be accomplished by 2011.

"This certainly has been the year of DNSSEC," Joffe said. "We’ve been at it for 13 years, but this is the year DNSSEC became real."

Some technical glitches remain with DNSSEC, and experts warn that Web sites may be unavailable when their domains switch to the new security protocol because of configuration problems.

"The largest operational hurdles that we’ve seen have been some small home routers and some intrusion detection systems and firewalls with default configurations that have trouble with DNSSEC," Rose said. "Users have to go back and reconfigure those systems for larger responses to handle the keys and signatures that come with DNSSEC."

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