Jianjun Chen

Assistant Professor at Tsinghua University working on Network Security

Office: Room 1-213, FIT building, Tsinghua University, Beijing, China

Email: jianjun [AT] tsinghua.edu.cn
jianjun [AT] icsi.berkeley.edu
cjj [AT] cs.uchicago.edu

  I'm looking for self-motivated Ph.D., master and undergradute students! Please feel free to email me.

Me and My Research

I am an assistant professor at the Institute for Network Sciences and Cyberspace at Tsinghua University. Before joining Tsinghua, I was a postdoctoral researcher at UC Berkeley (worked with Prof. Vern Paxson) and the University of Chicago (worked with Prof. Nick Feamster). I received my Ph.D. in Computer Science at Tsinghua University (advised by Prof. Haixin Duan) in 2018.

My research interest focus on network security, protocol security, and system security. I'm particularly interested in discovering and mitigating new security vulnerabilities in widely-used Internet protocols and systems, such as HTTP protocol, CDN system, email system, web browsers.

My research received two Distinguished Paper Awards (NDSS 2016 and USENIX security 2020) on the top-tier security conferences, and led to many real-world security responses, such as patches in popular HTTP implementations (e.g., Squid, Chrome, Firefox), security advisories by industrial companies (e.g., Akamai, Cloudflare, Apple), web standard change, and a new IETF RFC (RFC 8586).


A Large-scale and Longitudinal Measurement Study of DKIM Deployment
31th USENIX Conference on Security Symposium
Chuhan Wang, Kaiwen Shen, Minglei Guo, Yuxuan Zhao, Mingming Zhang, Jianjun Chen, Baojun Liu, Xiaofeng Zheng, Haixin Duan, Yanzhong Lin, Qingfeng Pan
USENIX Security'22
HDiff: A Semi-automatic Framework for Discovering Semantic Gap Attack in HTTP Implementations
52nd Annual IEEE/IFIP International Conference on Dependable Systems and Networks
Kaiwen Shen, Jianyu Lu, Yaru Yang, Jianjun Chen, Mingming Zhang, Haixin Duan, Jia Zhang, Xiaofeng Zheng
Best Paper Award Runners Up
Composition Kills: A Case Study of Email Sender Authentication
29th USENIX Conference on Security Symposium
Jianjun Chen,Vern Paxson, Jian Jiang
Invited to appear in USENIX ;login:, 2021(Invited Article)
Presented at BlackHat USA 2020 (talk abstract)
paper slides talk code
Coverage: Wired, CSO online, and Dark reading
USENIX Security'20
Distinguished Paper Award
CDN Judo: Breaking the CDN DoS Protection with Itself
Proceedings 2020 Network and Distributed System Security Symposium
Run Guo, Weizhong Li, Baojun Liu, Shuang Hao, Jia Zhang, Haixin Duan, Kaiwen Sheng, Jianjun Chen,Ying Liu
paper slides
We Still Don’t Have Secure Cross-Domain Requests: an Empirical Study of CORS
27th USENIX Conference on Security Symposium
Jianjun Chen, Jian Jiang, Haixin Duan, Tao Wan, Shuo Chen, Vern Paxson, Min Yang
Presented at DEFCON China 2018 (talk abstract)
paper slides talk code
USENIX Security'18
Abusing CDNs for Fun and Profit: Security Issues in CDNs’ Origin Validation
IEEE 37th Symposium on Reliable Distributed Systems
Run Guo; Jianjun Chen; Baojun Liu; Jia Zhang; Chao Zhang; Haixin Duan; Tao Wan; Jian Jiang; Shuang Hao; Yaoqi Jia;
Forwarding Loop Attacks in Content Delivery Networks
Proceedings 2016 Network and Distributed System Security Symposium
Jianjun Chen; Jian Jiang; Xiaofeng Zheng; Haixin Duan; Jinjin Liang; Kang Li; Tao Wan; Vern Paxson;
paper slides
Distinguished Paper Award
Host of Troubles: Multiple Host Ambiguities in HTTP Implementations
23rd ACM SIGSAC Conference on Computer and Communications Security
Jianjun Chen, Jian Jiang, Haixin Duan, Nicholas Weaver, Tao Wan, Vern Paxson
paper slides talk website
Best Paper Nominee
Seeking Nonsense, Looking for Trouble: Efficient Promotional-Infection Detection through Semantic Inconsistency Search
2016 IEEE Symposium on Security and Privacy
Xiaojing Liao; Kan Yuan; XiaoFeng Wang; Zhongyu Pei; Hao Yang; Jianjun Chen; Haixin Duan; Kun Du; Eihal Alowaisheq; Sumayah Alrwais; Luyi Xing; Raheem Beyah;

Professional Experience

  • Assistant Professor, Tsinghua University
  • Oct 2021 - Present
  • Postdoctoral Fellow, University of Chicago
  • Apr 2021 - Sep 2021
  • Postdoctoral Fellow, UC Berkeley
  • Aug 2018 - Apr 2021

    Honors & Awards

  • Distinguished Paper Award, USENIX Security 2020
  • 2020
  • ACM China SIGSAC Doctoral Dissertation Award
  • 2019
  • Distinguished Paper Award, Network and Distributed System Symposium (NDSS) 2016
  • 2016
  • National Scholarship, Ministry of Education, China
  • 2012
  • National Endeavor Scholarship, Ministry of Education, China
  • 2011