Israeli cybersecurity researchers have disclosed details about a new flaw impacting DNS protocol that can be exploited to launch amplified, large-scale distributed denial-of-service (DDoS) attacks to takedown targeted websites.
Called NXNSAttack, the flaw hinges on the DNS delegation mechanism to force DNS resolvers to generate more DNS queries to authoritative servers of attacker’s choice, potentially causing a botnet-scale disruption to online services.
“We show that the number of DNS messages exchanged in a typical resolution process might be much higher in practice than what is expected in theory, mainly due to a proactive resolution of name-servers’ IP addresses,” the researchers said in the paper.
“We show how this inefficiency becomes a bottleneck and might be used to mount a devastating attack against either or both, recursive resolvers and authoritative servers.”
Following responsible disclosure of NXNSAttack, several of the companies in charge of the internet infrastructure, including PowerDNS (CVE-2020-10995), CZ.NIC (CVE-2020-12667), Cloudflare, Google, Amazon, Microsoft, Oracle-owned Dyn, Verisign, and IBM Quad9, have patched their software to address the problem.
The DNS infrastructure has been previously at the receiving end of a rash of DDoS attacks through the infamous Mirai botnet, including those against Dyn DNS service in 2016, crippling some of the world’s biggest sites, including Twitter, Netflix, Amazon, and Spotify.
images from Hacker News