ICANN DNS Symposium | May 2021


In today’s DNS infrastructure, DNS forwarders are devices standing in between DNS clients and recursive resolvers. The devices often serve as ingress servers for DNS clients, and instead of resolving queries, they pass the DNS requests to other servers. Because of the advantages and several use cases, DNS forwarders are widely deployed and queried by Internet users. However, studies have shown that DNS forwarders can be more vulnerable devices in the DNS infrastructure. In this paper, we present a cache poisoning attack targeting DNS forwarders. Through this attack, attackers can inject rogue records of arbitrary victim domain names using a controlled domain, and circumvent widely-deployed cache poisoning defences. By performing tests on popular home router models and DNS software, we find several vulnerable implementations, including those of large vendors (e.g., D-Link, Linksys, dnsmasq and MS DNS). Further, through a nationwide measurement, we estimate the population of Chinese mobile clients which are using vulnerable DNS forwarders. We have been reporting the issue to the affected vendors, and so far have received positive feedback from three of them. Our work further demonstrates that DNS forwarders can be a soft spot in the DNS infrastructure, and calls for attention as well as implementation guidelines from the community.

May 25, 2021 12:00 PM — May 27, 2021 3:45 PM

In the 4th ICANN DNS Symposium (IDS 2021, virtually) , I presented a novel DNS cache poisoning attack (introduced by Xiaofeng Zheng from our lab) to the audiences.

Xiang Li
Xiang Li
Ph.D. Candidate in Cyberspace Security (Tsinghua University)

Xiang Li is a 5th-year Ph.D. candidate at the Institute of Network Science and Cyberspace, Tsinghua University, advised by Professors Qi Li and Haixin Duan. His research interests include network security, protocol security, IPv6 security, DNS security, Internet measurement, network & protocol fuzzing, network vulnerability discovery & attack, and underground economy with 15 research papers. As the first author, he has published many research papers at all top-tier security conferences, including Oakland S&P, USENIX Security, CCS, NDSS, and Black Hat (Asia, USA, and Europe). He has obtained over 180 CVE/CNVD vulnerability numbers, more than $11,600 rewards, 290+ GitHub stars, multiple CERT reports, 60+ news coverage, and RFC acknowledgement. He got multiple prizes, such as 1st prize of IPv6 Technology Application Innovation Competition, Tsinghua Outstanding Scholarship, LongFor Excellent Scholarship, National Scholarship, and 2nd prize of GeekCon 2023 DAF Contest.