Harold Kim
Backend Developer • Security Researcher
github stypremail me@harold.kim  · root@stypr.compubkey›   ctftime stypr


Security Engineer, LINE Corporation
Tokyo, Japan
Feb 2019 -
8 months
» Mainly focusing on internal security pentests on LINE and its affiliates' products.
» Developed automated security analysis tools and tools for detecting potential risks.
» Reviewing bugbounty reports, recruitment support.
Security Researcher, SEWorks Inc.
Seoul, South Korea
June 2014 - Nov 2018
4y 5 months
» Focused mainly on core server management and backend service development.
» Developed core products, including product maintanence. (Used python, GoLang+Redis, PHP, Java, etc.)
» Frequently performed vulnerability checks and penetration tests on flagship products.
» Focused on security researches for future developments.
Signaller, ROK Army
Paju, South Korea
Nov 2016 - Aug 2018
1y 8 months
» Discharged as Sergeant. Received many awards while working in the army.
» Maintained internal systems, managed and monitored security firewalls.
» Developed an application which automatically checks security status and prints out the report on every boot.
» Developed a pentest software to increase awareness on side-effects of using smartphones in the army.


Undergraduate Student, University of Toronto Sept. 2014 - June 2015
9 months
» Currently studying as an undergraduate, and is going to acquire a Bachelor’s degree at some point.
» Currently on a long leave for jobs.
International Baccalaureate Diploma Sept. 2012 - June 2014
1y 9 months
» Acquired International Baccalaureate Diploma for Secondary School.
» Studied in an Indian International school.


2019 Finalist, DEFCON 26 CTF Las Vegas, NV
2019 1st place, 0CTF 2019 Shanghai, China
2018 Finalist, Real World CTF 2018 Zhengzhou, China
2017 Finalist, CodeGate CTF 2017 Seoul, South Korea
2016 1st place on ctftime as team dcua.
2016 2nd place, EKOPARTY CTF 2016 Latin America
2016 2nd place, Silk Road CTF 2016 Karamay, China
2016 1st place, ASIS CTF 2016 Finals Tehran, Iran
2016 1st place, C4CTF 2016 Riyadh, Saudi Arabia
2016 1st place, TU CTF 2016 Tulsa, OK
2016 1st place, Sharif University CTF Tehran, Iran
2016 2nd place, Internetwache CTF Berlin, Germany
2016 Finalist, PHDays 2016 Moscow, Russia
2015 1st place, Hack Zone Tunisia 2015 Manouba, Tunisia
2015 1st place, Break In 2015 Hyderabad, India
2015 Finalist, CSAW CTF 15 Hacking Competition Brooklyn, NY
2014 Finalist, CSAW CTF 14 Hacking Competition Brooklyn, NY
2014 Finalist, DEFCON 22nd CTF Las Vegas, NV
2014 2nd place. Olympic Sochi CTF 2015
2019 1st place, Cyber Operations Challenge (Whitehat Contest) Seoul, South Korea
2018 1st place, Korean Army Hacking Defense Contest Daejeon, South Korea
2015 1st place, 14th HUST Hacking Festival Seoul, South Korea
2015 1st place, 2015 Inc0gnito Hacking Competition Seoul, South Korea
» I’ve done a lot of competitions so far since 2012. Writeups on some of these are archived in github.
» If you need writeups on ones that I didn't publish, please feel free to contact me.


CTF Organizer and Security Challenge Author 2014 - PRESENT
2014-2016 Organizer and Author, KAIST and POSTECH Science War (Hacking)
  » Some of challenged released in the Science War can now be played on Stereotyped Challenges
2018 Author, moehost and gameshop, ASISCTF 2018 Quals. Writeups are available here.
  More to come...
Web Fuzzer Development and its Utilization June 2014
Talked on WOWHACKER 2nd Seminar. Seoul, Korea

» a.k.a. Introduction to web fuzzer development.
» Demonstrated the process of web fuzzer development and its utilization, including the practical usage of fuzzers and its utilizations.
» Presentations available at //goo.gl/VabWPK
Stereotyped Challenges Oct. 2014 - PRESENT
5y 0 month

» Operating and developing a website consisting of extremely technical offensive security challenges.
» Most of challenges are solely developed and tested by me. all challenges are sandboxed seperately.
» Sourcecode of the website is currently available on //github.com/stypr/chall.stypr.com