KAIST

< Team 0x4b52 >

KAIST (President Choongsik Bae) announced on August 14 that the Korean hacking team “0x4b52,” which included Professor Insu Yun of the School of Electrical Engineering as well as numerous KAIST students and alumni, finished second at DEF CON CTF 2026, held in Las Vegas, the United States, from August 7 to 9.

Comprising approximately 30 Korean hackers, 0x4b52 competed against world-class multinational teams to claim the runner-up position. This marks the best result achieved by an all-Korean team at DEF CON CTF since the Korean team “DEFK0R” won the competition in 2015.

Of the 686 teams that participated in the qualifiers, only the top 12 advanced to the finals. After qualifying in fifth place, 0x4b52 climbed the rankings to finish second overall. The achievement is particularly significant because KAIST members from different generations, including undergraduate and graduate students as well as alumni, competed together as one team against the world’s leading hackers.

“I find it deeply meaningful that our students and alumni demonstrated their outstanding capabilities on a stage where the world’s most accomplished hackers compete,” said KAIST President Choongsik Bae. “This achievement is even more significant because it was accomplished through a joint effort by multiple generations of KAIST members, from undergraduate and graduate students to alumni.”

President Bae added, “In the era of AI, a strong foundation and domain expertise are more important than ever. KAIST will actively support students in challenging themselves in areas of interest from the undergraduate level, building expertise through hands-on experience and research, and growing into global talents who can take the lead in leveraging AI and forge new paths.”

DEF CON CTF is a flagship event of DEF CON, one of the world’s largest hacker conferences. It is an international hacking competition in which elite hackers from around the globe test their capabilities in system security and hacking. This year’s finals were held as one of the main events of DEF CON 34 in Las Vegas. The multinational team “Blue Water” won the championship, while the Korean team 0x4b52 finished second.

Capture The Flag (CTF) is a type of hacking competition in which teams earn points by analyzing vulnerabilities in given systems and software and conducting offensive and defensive operations. Participants must analyze systems and software, identify vulnerabilities, and compete against opposing teams within a limited time. The competition therefore requires advanced technical expertise as well as close teamwork and strategic judgment.

This year’s qualifiers featured challenges across a wide range of information security fields, including binary exploitation, reverse engineering, cryptography, and web exploitation.

0x4b52 is a Korean team formed primarily by members of the hacking team from Korea, HypeBoy, and Professor Insu Yun’s laboratory at KAIST. Approximately one-third of the team’s roughly 30 members are currently affiliated with or previously worked in Professor Yun’s Hacking Lab.

Numerous other KAIST students and alumni also participated. Many began exploring system hacking and security research as undergraduates, including through the information security club “GoN.” They further developed their expertise through coursework, research, and other opportunities in the School of Electrical Engineering, the School of Computing, and the Graduate School of Information Security. Undergraduate and master’s and doctoral students competed on the same team alongside alumni now working in industry and research institutions, bringing together different generations of KAIST hackers.

Professor Yun’s research team, one of the central groups within 0x4b52, also reached the top of a major global cybersecurity competition in Las Vegas last year. Together with researchers from Samsung Research, POSTECH, and the Georgia Institute of Technology, Professor Yun’s team formed “Team Atlanta” and participated in the AI Cyber Challenge (AIxCC), organized by the U.S. Defense Advanced Research Projects Agency (DARPA). The team won the final round held at DEF CON 33 in August 2025.

AIxCC is a competition focused on technologies that use artificial intelligence to automatically detect and repair software vulnerabilities. Team Atlanta received a prize of USD 4 million for winning the finals. At this year’s DEF CON CTF, Professor Yun’s research team competed alongside KAIST students and alumni against some of the world’s leading teams in system security. This follows the team’s victory last year in a global competition for AI-powered autonomous cyber defense technology, marking back-to-back achievements on the international stage.

The achievement also highlights KAIST’s approach to developing information security talent—giving students hands-on hacking experience as undergraduates, supporting them as they pursue specialized security research in graduate school, and helping them build professional expertise after graduation.

At KAIST, undergraduate students gain hands-on experience analyzing real-world systems and identifying vulnerabilities through coursework and student clubs. At the graduate level, students pursue specialized system security research in areas such as software vulnerability analysis, program analysis, and automated vulnerability detection. Meanwhile, KAIST is expanding its education and research capacity in information security by training master’s- and doctoral-level specialists and participating in the government-supported Information Security Specialized University Program.

“This achievement reflects the collective effort of students who have learned from one another, gained hands-on experience, and grown together over many years,” said Professor Insu Yun. “I also became deeply involved in information security through GoN as an undergraduate at KAIST. That makes it particularly meaningful to see students and alumni from different generations come together, compete as a team against some of the world’s best hackers, and achieve this result.”

< DEF CON CTF Final Standings >