| Nick Name | |
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ยป extr |
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| Interested In | |
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ยป Cyber Threat Intelligence ยป Web Service Development ยป Tea & Whisky |
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| Skills | |||||||
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| CTF & Research Groups | |||||||||||||
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| CERT, KakaoBank Gyeonggi, South Korea |
May 2026 - Present - |
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ยป - |
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| CERT, Bithumb Seoul, South Korea |
Feb 2025 - Apr 2026 - |
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ยป Leveraged AI-driven CTI analysis to produce internal threat intelligence reports, and implemented SOAR integrations and custom actions to streamline response workflows. ยป Conducted continuous EDR event analysis to strengthen incident prevention and response, and developed SIEM detections/use-cases. ยป Established and operated SCA/OSS supply-chain security policies to block vulnerable or malicious components from entering the SDLC. ยป Planned and ran monthly phishing simulations and biannual crisis response drills (DDoS/phishing) to improve organizational readiness. |
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| Security Service Developer, NCSOFT Gyeonggi, South Korea |
May 2021 - Dec 2024 3 years, 8 months |
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ยป Developed an internal security policy lookup portal for the security center and company-wide users. ยป Designed and implemented a security review management system for game, web, and API service deployments. ยป Built a Security Appliance API Gateway to streamline secure development and standardize security controls. ยป Developed malicious network traffic detection modules and supported ongoing event analysis and monitoring. |
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| DFIR Specialist, Plainbit Co., Ltd. Gyeonggi, South Korea |
Aug 2019 - May 2021 1 year, 10 months |
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ยป Supported digital evidence acquisition and forensic analysis across multiple small-to-mid scale incidents, including ransomware and APT intrusions. ยป Built automation tools to accelerate triage and analysis workflows in time- and resource-constrained investigations. |
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| Senior Researcher, Culture Makers Seoul, South Korea |
Nov 2018 - Jul 2019 8 months |
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ยป Military Service (Skilled Industrial Personnel) ยป Organized information security competitions and produced infosec training/educational content. ยป Managed virtual lab networks using VMware vSphere and developed supporting administration/management tools. |
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| Security Researcher, SEWorks Inc. Seoul, South Korea / CA, United States |
Feb 2017 - Nov 2018 1 year, 10 months |
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ยป Military Service (Skilled Industrial Personnel) ยป Developed automation tools to support product operations and backend server administration. ยป Built analysis modules for detecting and analyzing malicious Android APKs. ยป Contributed to the development of a game engine obfuscation module based on LLVM Obfuscator. |
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| Software Vulnerability Analyst, WINS Co., LTD. Gyeonggi, South Korea |
Jan 2016 - Jan 2017 1 year |
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ยป Conducted vulnerability research and analyzed 1-day vulnerabilities. ยป Actively participated in incident response engagements as a CERT analyst, performing root-cause analysis and impact assessment. |
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| Security Researcher, Divine Security Gyeonggi, South Korea |
Jan 2015 - Jun 2015 6 months |
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ยป Developed a malicious APK analysis module for malware triage and behavioral analysis. |
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| Security Consultant, ***** Seoul, South Korea |
Mar 2013 - Aug 2013 6 months |
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ยป Performed black-box and white-box penetration testing across web and application targets. ยป Supported G-ISMS/ISMS compliance initiatives, including security assessments and documentation. |
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| Only showing the results of top 3 places and finalists of memorable CTFs, |
| International | ||
| 2020 | 1st place, InterKosen CTF | Japan |
| 2020 | 1st place, Defenit CTF | South Korea |
| 2019 | 1st place, Harekaze CTF | Japan |
| 2019 | 3rd place, DFRWS IoT Forensic Challenge, write-up | United States |
| 2018 | 2nd place, Digital Forensic Challenge 2018 | South Korea |
| 2017 | 2nd place, ASIS CTF Finals | Iran |
| 2017 | 3rd place, Volga CTF | Russia |
| 2016 | Finalist, TrendMicro CTF | Japan |
| 2016 | 2nd place, EKOPARTY CTF 2016 | Argentina |
| 2016 | 1st place, ASIS CTF Finals | Iran |
| 2016 | 1st place, Volga CTF | Russia |
| 2014 | Finalist, DEFCON 22 CTF | United States |
| Domestic | ||
| 2022 | Finalist, Cyber Conflict Exercise | Daegu, South Korea |
| 2019 | Finalist, Cyber Conflict Exercise | Busan, South Korea |
| 2015 | 1st place, 14th HUST Hacking Festival | Seoul, South Korea |
| 2015 | 1st place, Find the Digital Culprit | Seoul, South Korea |
| 2015 | 1st place, Inc0gnito Hacking Competition | Seoul, South Korea |
| 2014 | 3rd place, Find the Digital Culprit | Seoul, South Korea |
| 2013 | 3rd place, Whitehat Contest | Seoul, South Korea |
| 2013 | 3rd place, Find the Digital Culprit | Seoul, South Korea |
| 2011 | Bronze Prize, Soonchunhyang University 'Y.I.S.F.' | Asan, South Korea |
| 2011 | Bronze Prize, Tongmyong University 'Information Science Olympiad' | Busan, South Korea |
| Software Vulnerability Reports | |||||||||||||||||||||
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| CTF Organizer and Challenge Author | |||||||||||||||||||
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| Presentation | |||||
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