Black Hat Europe 2023


In this paper, we present a new DNS amplification attack, named TsuKing. Instead of exploiting individual DNS resolvers independently to achieve an amplification effect, TsuKing deftly coordinates numerous vulnerable DNS resolvers and crafted queries together to form potent DoS amplifiers. We demonstrate that with TsuKing, an initial small amplification factor can increase exponentially through the internal layers of coordinated amplifiers, resulting in an extremely powerful amplification attack. TsuKing has three variants, including DNSRetry, DNSChain, and DNSLoop, all of which exploit a suite of inconsistent DNS implementations to achieve enormous amplification effect. With comprehensive measurements, we found that about 14.5% of 1.3M open DNS resolvers are potentially vulnerable to TsuKing. Real-world controlled evaluations indicated that attackers can achieve a packet amplification factor of at least 3,700× (DNSChain). We have reported vulnerabilities to affected vendors and provided them with mitigation recommendations. We have received positive responses from 6 vendors, including Unbound, MikroTik, and AliDNS, and 3 CVEs were assigned. Some of them are implementing our recommendations.

Dec 6, 2023 12:00 AM — 11:59 PM
One Western Gateway, London, E16 1XL

In Black Hat Europe 2023, Professor Haixin Duan presented our work: “TsuKing: Coordinating DNS Resolvers and Queries into Potent DoS Amplifiers”.

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 17 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 190 CVE/CNVD vulnerability numbers, more than $11,600 rewards, 306+ 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, 2nd prize of GeekCon 2023 DAF Contest, National Scholarship, Wang Dazhong Scholarship, and Tsinghua Outstanding Scholarship.