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Friday, 07 May 2021 10:21

DNS vulnerability spotted by InternetNZ in 2020, now fixed

DNS vulnerability spotted by InternetNZ in 2020, now fixed Image by Markus Winkler from Pixabay

InternetNZ, the domain name authority for New Zealand, says it has fixed a vulnerability in authoritative DNS servers like those run by the top-level domain operators.

This could have been used to carry out denial-of-service attacks across the Internet, the company said in a statement.

The vulnerability, given the name TsuNAME, was spotted in February 2020 in the .nz registry.

The vulnerability needed cyclic dependent NS records and vulnerable resolvers to be exploited; user queries would serve to start or drive the process.

Two .nz domains were unknowingly misconfigured with cyclic dependencies and this led to a 50% surge in DNS traffic for the entire .nz infrastructure.

The problem was studied and replicated by experts from InternetNZ, SIDN Labs (the organisation running .nl), and the University of Southern California Information Science Institute (USC/ISI).

"Google Public DNS was the main affected party by this vulnerability," said InternetNZ's chief ccientist Sebastian Castro.

"They received a private responsible disclosure from our group in October 2020 and have repaired their code since then. We also reached out to Cisco, whose Public DNS was affected as well, and it is now fixed."

The research group has published a tool known as CycleHunter to check for the TsuNAME flaw. A security advisory and a technical paper have also been issued.

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Sam Varghese

Sam Varghese has been writing for iTWire since 2006, a year after the site came into existence. For nearly a decade thereafter, he wrote mostly about free and open source software, based on his own use of this genre of software. Since May 2016, he has been writing across many areas of technology. He has been a journalist for nearly 40 years in India (Indian Express and Deccan Herald), the UAE (Khaleej Times) and Australia (Daily Commercial News (now defunct) and The Age). His personal blog is titled Irregular Expression.

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