DNS Management Provider Hit With Sophisticated, 'Precise' DDoS Attacks

A sophisticated, sustained, and ongoing distributed denial-of-service (DDoS) attack on DNS and traffic management firm NS1 highlights what the company’s CEO says is a clear escalation in attacks against organizations in this space over the past several months.

Kris Beevers says the DDoS attacks against his company’s managed DNS network and other infrastructure resources began early on Monday, May 16, and haven’t ceased since then. For more than 10 days, unknown attackers have hit NS1’s infrastructure with a degree of determination and sophistication not normally seen in such attacks, Beevers says.

In the early stages, the DDoS attacks caused partial service delivery failure in some parts of NS1 networks, especially in Europe. But mitigation measures have been put in place since then to ensure uninterrupted service.

What makes the attack different is the sheer variety of strategies that are being employed by the attackers to try and disrupt NS1’s services, Beevers told Dark Reading.

Unlike simple volumetric attacks, where adversaries try to overwhelm a victim’s network with huge volumes of malicious data, the threat actors in this case have also employed direct DNS look-up attacks, and attacks that are aware of how DNS works. Also targeted in the attacks are several upstream providers who bring traffic to NS1, Beevers says.

“What is interesting is how precise the attacks are,” he said. “They are not gigantic. They are not small, either. “They are serious in terms of volume, but what is much more interesting is the type of traffic” used in the DDoS attacks.

The threat actors appear to have some level of knowledge about NS1’s traffic and infrastructure and have been able to direct their DDoS streams at different targets. NS1’s European infrastructure has been the most heavily targeted. But the company’s networks in Asia and in the western US also have been hit.

A bulk of the DDoS streams are being launched from Russia and parts of the former Soviet Union, Beever says. Systems based in China and the US, also have been used to launch the attacks.

The focus has been on “specifically impacting our ability to deliver service and to distinguish between good and bad traffic,” he says. “What we have had to do is to evolve our filtering strategies rapidly,” in order to be able to filter out malicious traffic while allowing legitimate traffic to flow through.

In addition to going after NS1’s core DNS delivery infrastructure, the threat actors have also directed DDoS traffic against the rest of the company’s infrastructure, including its corporate website and status update page. The attack pattern makes it clear that the adversaries are targeting NS1 specifically and not any of its customers.

“During last week's attacks, the primary customer impact came from malicious direct DNS query traffic designed specifically to look like legitimate DNS traffic,” Beevers wrote in a blog explaining the issue to customers. “In some cases, this traffic resulted in service impacting load on our DNS delivery systems due to the unique nature and volume of the traffic.” NS1 has implemented configuration changes and software updates as well as new online filtering capabilities to deal with the DDoS attacks, he said.

Attacks against DNS providers and content delivery networks can have broad repercussions. NS1’s DNS management platform, for instance, handles several hundreds of billions of DNS queries per month for some of the largest properties on the Internet, according to Beever. Any attack that disrupts NS1’s ability to deliver these services could have serious implications for those Internet properties in the form of slow page loads and DNS timeouts.

According to Beever, conversations with other CDNs and DNS providers show that similar attacks have been going on for the past several months.

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