VeriSign Flexes DNS Security Muscle

All might seem quiet on Internet's Domain Name Server (DNS) front since the February attack that crippled two of the Internet's 13 DNS root servers. But inside VeriSign, which maintains some of those core servers, there have been plenty of skirmishes. (See DNS Attack: Only a Warning Shot? and VeriSign Ups the DNS Ante ).

"There have been a number of attacks on the [Internet] DNS infrastructure over the last six months, but not to the extent of previous ones," says Ken Silva, chief security officer at VeriSign, which said today that it's ahead of schedule in Project Titan, its $100 million-plus DNS infrastructure security and capacity upgrade. "They haven't gone quiet just because you're not reading about them."

DNS has become a soft target for attackers because it's not easy to protect. It requires no handshake between the attacker and the victim, which means that attackers can quickly overwhelm the system -- often with a distributed denial-of-service (DDOS) attack.

"We put in some software enhancements to counter some of those threats that are specific to DNS, where certain actions can cause it to come under stress," says Silva, who didn't provide details of the latest DNS attacks.

"We've long expressed that not all of the Internet's DNS domains are as well protected as they should be against DDOS and some spoofing attacks. We think we are on track with this… and this could set the standard for [the way] this ought to be done."

VeriSign, which first revealed Project Titan in the wake of the February DNS attack, has completed its North American edge and resolution site expansion, and will open a new data center in Delaware in the first quarter of next year, Silva says. And it's about halfway finished building a new one in Switzerland -- all part of its strategy to further distribute the DNS server infrastructure for the .com and .net domains that it manages.

The company also has upped its DNS query capacity from 400 billion queries per day to about 2 trillion, and it plans to expand to support 4 trillion queries a day by 2010. Bandwidth-wise, VeriSign's servers are now 100 Gbit/s, up from 20 Gbit/s, and the plan is to go to 200 Gbit/s by the end of the decade. The company has expanded and made other enhancements to its DNS infrastructure that also help it better isolate the source of an attack, according to Silva.

Among the expanded features is "anycasting," which is the key to distributing and protecting the DNS servers. Anycasting is the streaming of DNS queries to multiple servers so they don't get lost or jam up a given server. Anycasting was what saved the Net from more serious damage in the February attack. "We've even begun anycasting some of our big bandwidth sites as well," Silva says.

Anycasting is nothing new, however. "People have been doing that for years, but nobody is doing it at the scale that [VeriSign] is doing it," says Danny McPherson, chief research officer for Arbor Networks.

And even with anycasting, it's still tough to trace an attack to its source, VeriSign's Silva says. "So we took a blended approach of global anycasting with regional anycasting for a finer-grain [detection] to find out where the traffic is coming from."

VeriSign also has built an integrated network monitoring and security response infrastructure to help it better respond to threats to the .com and .net servers. "We can now spot well in advance problems like [shrinking] disk or memory capacity or CPU overload," which can signal an attack.

But like most other threats to infrastructure, beefing up DNS security is about keeping step with the bad guys' increasingly sophisticated and stealthy capabilities, such as botnets.

"The biggest threat to DNS has nothing to do with DNS, but rather, it has to do with overall capacity. We're in a situation where the bad guys are able to accumulate almost as much bandwidth as the good guys," says David Ulevitch, CEO of OpenDNS. "Mitigation techniques such as anycast help diffuse the situation by dividing the attacker's target into many pieces, but the problem still exists. It's just been cut up."

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