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LINE CTF 2025 serves as a collaborative platform for global security experts to exchange technical knowledge and tackle real-world cybersecurity challenges through a competitive framework. Under the newly integrated LY Corporation, the event evolved to prioritize anti-AI problem design and enhanced privacy protections, reinforcing its position as a top-tier competition in the Asian security community. The event successfully demonstrated that high-quality problem engineering and community-focused operations can drive both individual growth and organizational security excellence. ## Strategic Shift and AI-Resilient Design * **Multisite Collaboration:** While previous years were led primarily by the Japanese team, 2025 saw a shift where the Korean security team led preparations and the Vietnamese team contributed the highest volume of technical challenges. * **Counter-AI Engineering:** To maintain fairness in an era of LLMs, problems were specifically designed to mislead automated AI analysis, requiring human logic and deep conceptual understanding to arrive at the correct "flag." * **Systemic Integration:** This was the first year applying the unified LY Corporation administrative and approval processes, resulting in a more refined timeline for problem verification and quality control. ## Competition Format and Problem Engineering * **Jeopardy-Style Challenges:** The event featured 13 independent challenges—6 Web, 4 Pwnable, and 3 Reverse Engineering—where teams earned points based on difficulty. * **Three-Stage Validation:** Every problem underwent a rigorous cycle of idea conception, technical environment isolation/testing, and internal peer review to eliminate unintended "cheese" solutions or bugs. * **Technical Philosophy:** Problems were modeled after real-world service vulnerabilities and latest security trends, targeting a difficulty level that requires several hours of dedicated analysis by a skilled researcher. ## Platform Evolution and Performance * **Privacy-First Infrastructure:** The team customized the open-source CTFd framework to remove email-based registration, instead using a recovery-code system to ensure participant anonymity and data security. * **Growing Technical Prestige:** The competition’s rating on CTFtime (a global community platform) has climbed steadily over three years, reaching a weight of 66.5 in 2025, reflecting its high quality and difficulty. * **Competitive Results:** The Korean team "The Duck" maintained dominance with a third consecutive win, while the battle for second place was decided by a dramatic last-minute solve by the Japanese team "GMO Ierae." Participating in CTFs like LINE CTF offers an invaluable practical learning environment for security engineers to master vulnerability analysis and exploit development. Aspiring and professional researchers are encouraged to engage with these challenges to sharpen their analytical skills and contribute to a more robust, collaborative global security culture.