NDSS 2024 - Understanding the Implementation and Security Implications of Protective DNS Services

SESSION 3A-2 Understanding the Implementation and Security Implications of Protective DNS Services

Domain names are often registered and abused for harmful and illegal Internet activities. To mitigate such threats, as an emerging security service, Protective DNS (PDNS) blocks access to harmful content by proactively offering rewritten DNS responses, which resolve malicious domains to controlled hosts. While it has become an effective tool against cybercrime, given their implementation divergence, little has been done from the security community in understanding the deployment, operational status and security policies of PDNS services.

In this paper, we present a large-scale measurement study of the deployment and security implications of open PDNS services. We first perform empirical analysis over 28 popular PDNS providers and summarize major formats of DNS rewriting policies. Then, powered by the derived rules, we design a methodology that identifies intentional DNS rewriting enforced by open PDNS servers in the wild. Our findings are multi-faceted. On the plus side, the deployment of PDNS is now starting to scale: we identify 17,601 DNS servers (9.1% of all probed) offering such service. For DNS clients, switching from regular DNS to PDNS induces negligible query latency, despite additional steps (e.g., checking against threat intelligence and rewriting DNS response) being required from the server side. However, we also find flaws and vulnerabilities within PDNS implementation, including evasion of blocking policies and denial of service. Through responsible vulnerability disclosure, we have received 12 audit assessment results of high-risk vulnerabilities. Our study calls for proper guidance and best practices for secure PDNS operation.

PAPER
https://www.ndss-symposium.org/wp-con...

AUTHORS
Mingxuan Liu (Zhongguancun Laboratory; Tsinghua University), Yiming Zhang (Tsinghua University), Xiang Li (Tsinghua University), Chaoyi Lu (Tsinghua University), Baojun Liu (Tsinghua University), Haixin Duan (Tsinghua University; Zhongguancun Laboratory), Xiaofeng Zheng (Institute for Network Sciences and Cyberspace, Tsinghua University; QiAnXin Technology Research Institute & Legendsec Information Technology (Beijing) Inc.)

Network and Distributed System Security (NDSS) Symposium 2024, 26 February – 1 March 2024 in San Diego, California.

ABOUT NDSS
The Network and Distributed System Security Symposium (NDSS) fosters information exchange among researchers and practitioners of network and distributed system security. The target audience includes those interested in practical aspects of network and distributed system security, with a focus on actual system design and implementation. A major goal is to encourage and enable the Internet community to apply, deploy, and advance the state of available security technologies.
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