I am an Assistant Professor in Department of Electrical Engineering and Computer Science (EECS) at DGIST. I earned my Ph.D in Computer Science from Purdue University under the direction of Professor Xiangyu Zhang. My research interest lies in software and systems security in general. In particular, I am currently focusing on security and reliability of autonomous cyber-physical systems, such as an unmanned aerial vehicle (UAV, commonly known as a drone), a self-driving car. My current work deals with fundamental security issues in these CPS, including attack and defense, vulnerability discovery and elimination, and CPS forensics.

TOP 4 Security Conferences (S&P, CCS, USENIX, NDSS)
TOP 4 Software Engineering (ICSE, FSE, ASE, ISSTA)


• [Top-tier] Physical Attack on Monocular Depth Estimation in Autonomous Driving with Optimal Adversarial Patches
  Zhiyuan Cheng, James Liang, Hongjun Choi, Guanhong Tao, Zhiwen Cao, Dongfang Liu, and Xiangyu Zhang,
  Proceedings of the 17th European Conference on Computer Vision (ECCV 2022), Tel-Aviv, Israel, Oct 23-27 2022.
• [Top-tier] RVPLAYER: Robotic Vehicle Forensics by Replay with What-if Reasoning
  Hongjun Choi, Zhiyuan Cheng, and Xiangyu Zhang,
  Proceedings of the 29th Network and Distributed System Security Symposium (NDSS 2022), San Diego, CA, April 2022. Acceptance Rate: 14.0% (53/377)
• [Top-tier] PHYSFRAME: Type Checking Physical Frames of Reference for Robotic Systems
  Sayali Kate, Michael Chinn, Hongjun Choi, Xiangyu Zhang, and Sebastian Elbaum,
  Proceedings of the ACM Joint European Software Engineering Conference and Symposium on the Foundations of Software Engineering (ESEC/FSE 2021) , Athens, Greece, August 2021. Acceptance Rate: 24.5% (97/396)
• [Top-tier] Cyber-Physical Inconsistency Vulnerability Identification for Safety Checks in Robotic Vehicles,
  Hongjun Choi, Sayali Kate, Yousra Aafer, Xiangyu Zhang, and Dongyan Xu,
  Proceedings of the 27th ACM Conference on Computer and Communications Security (CCS 2020), Orland (Virtual Event), USA, November 2020. Acceptance Rate: 16.9% (121/715)
• Software-based Realtime Recovery from Sensor Attacks on Robotic Vehicles
  Hongjun Choi, Sayali Kate, Yousra Affer, Xinagyu Zhang, and Dongyan Xu,
  Proceedings of the 23rd International Symposium on Research in Attacks, Intrusions and Defenses (RAID 2020), Donostia / San Sebastian, Spain (Virtual Event), October, 2020. Acceptance Rate: 25.6% (31/121)
• White-Box Program Tuning,
  Wen-Chuan Lee, Yingqi Liu, Peng Liu, Shiqing Ma, Hongjun Choi, Xiangyu Zhang, and Rajiv Gupta,
  Proceedings of the 2019 IEEE/ACM International Symposium on Code Generation and Optimization (CGO 2019), Washington DC, USA, Feb 2019. Acceptance Rate: 31% (27/69)
• [Top-tier] Detecting Attacks Against Robotic Vehicles: A Control Invariant Approach,
  Hongjun Choi, Wen-Chuan Lee, Yousra Aafer, Fan Fei, Zhan Tu, Xiangyu Zhang, Dongyan Xu, and Xinyan Deng,
  Proceedings of the 25th ACM Conference on Computer and Communications Security (CCS 2018), Toronto, Canada, November 2018. Acceptance Rate: 16.6% (134/809)
• [Top-tier] Securing Real-Time Microcontroller Systems through Customized Memory View Switching,
  Chung Hwan Kim, Taegyu Kim, Hongjun Choi, Zhongshu Gu, Byoungyoung Lee, Xiangyu Zhang, and Dongyan Xu,
  Proceedings of the 25th Network and Distributed System Security Symposium (NDSS 2018), San Diego, CA, February 2018. Acceptance Rate: 21.5% (71/311)
• RevARM: A Platform-Agnostic ARM Binary Rewriter for Security Applications,
  Taegyu Kim, Chung Hwan Kim, Hongjun Choi, Yonghwi Kwon, Brendan Saltaformaggio, Xiangyu Zhang, and Dongyan Xu,
  Proceedings of the Annual Computer Security Applications Conference (ACSAC 2017), San Juan, PR, December 2017. Acceptance Rate: 19.7% (48/244)
• Eavesdropping on Fine-Grained User Activities Within Smartphone Apps Over Encrypted Network Traffic,
  Brendan Saltaformaggio, Hongjun Choi, Kristen Johnson, Yonghwi Kwon, Qi Zhang, Xiangyu Zhang, Dongyan Xu, and John Qian,
  Proceedings of the 10th USENIX Workshop on Offensive Technologies (WOOT'16), Austin, TX, August 2016. Acceptance Rate: 47.7% (21/44)

• CPS Attack Detection
  -  CI Monitoring: physical attack detection based on Control Invariant (CI) monitoring
  
• CPS Attack Resilience
  -  Software Sensor: the first software-based sensor approach for attack-resilient control of robotic vehicles
  
• CPS Control Program Analysis -- Vulnerability/Defects Anlaysis
  -  Control Program Analysis: automated Cyber-Physical inconsistency (CPi) vulnerability identification
  -  FrameChecker: a static anlysis tool for detecting reference frame inconsistencies [ artifact]
  
• CPS After-attack/accident Investigation
  -  CPS Forensics: post-mortem attack investigation of robotic vehicles
  
• Cyber-Physical Attacks
  -  Physical Attack on Autonomous Vehicles: optimal adversarial patches to attack monocular depth estimation modules in autonomous driving
  

• NRF Outstanding Young Researcher (우수신진연구) by National Research Foundation (NRF), 720,000K (KRW) for 3/2023-2/2028
• DGIST Faculty Start-up Fund (교원정착금) by Daegu Gyeongbuk Institute of Science & Technology (DGIST), 300,000K (KRW) for 9/2022-12/2025

Activities

• Program Committee:
  -  ACM Conference on Computer and Communications Security (CCS), Program Committee, 2023
  -  IEEE Symposium on Security and Privacy (IEEE S&P), Shadow Program Committee, 2021
  -  USENIX Security, Artifact Evaluation Committee, 2022
  -  IEEE Conference on Dependable and Secure Computing (IEEE DSC), Program Committee, 2022
  -  International Symposium on Research in Attacks, Intrusions and Defenses (RAID), Program Committee, 2023
• Sub-reviewer:
  -  ACM Conference on Computer and Communications Security (CCS), 2020, 2019, 2016, 2015
  -  USENIX Security Symposium (USENIX Security), 2022, 2021, 2018
  -  Annual IEEE/IFIP International Conference on Dependable Systems and Networks (DSN), 2015
  -  IEEE Secure Development Conference (SecDev), 2017
  -  International Symposium on Engineering Secure Software and Systems (ESSOS), 2017
  -  ACM SIGSOFT International Symposium on Foundations of Software Engineering (FSE), 2022, 2020, 2018, 2016
  -  International Conference on Software Engineering (ICSE), 2022, 2020, 2017
  -  ACM SIGSOFT International Symposium on Software Testing and Analysis (ISSTA), 2017
  
• Journal Reviewer:
  - IEEE Internet of Things Journal, 2020

• CSE405: Introduction to Computer Security (Undergraduate) [Spring 2023]
  
• IC899: Special Topics in Cyber-Physical Systems - CPS Security (Graduate) [Fall 2022]