VOLUME
Plan workouts, log sets, and track training with or without a personal trainer.
Next.js · Expo · SupabaseView project
Security researcher.
Back-end developer.
Master's student.
I'm Teun. I build web applications and research how systems can be compromised.
Responsible disclosure
Organizations where I've found and responsibly reported security vulnerabilities.
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Rijksoverheid
Website
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Belastingdienst
Hall of fame
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University of Amsterdam
Hall of fame
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Vrije Universiteit Amsterdam
Hall of fame
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Utrecht University
Website
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Leiden University Medical Center
Hall of fame
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Amsterdam UMC / VUmc
Website
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Wageningen University & Research
Website
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HAN University of Applied Sciences
Website
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AFAS Software
Website
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Dirk
Website
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Bovemij
Website
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ALDI SÜD
Hall of fame
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Shell
Website
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Amsterdam University of Applied Sciences
Hall of fame
Selected projects
Web applications, desktop tools, and interactive experiments.
ToolboxCraft
Install, open, and update Artcraft apps from one native desktop launcher.
Rust · egui · Native desktopView project
Bureau Profiel
A recruitment platform with a candidate questionnaire and an administration panel for finding suitable candidates.
Laravel · PHPView project
Maze Solver
Draw or generate a maze, compare six pathfinding algorithms, and watch each search unfold step by step.
JavaScript · Canvas · PathfindingView project
About me
I started with Media Development at Mediacollege Amsterdam, then studied HBO-ICT at the Amsterdam University of Applied Sciences. I graduated cum laude in 2026 and now study at the UvA.
Alongside my studies, I have built client applications at SMIT, interned with KPN’s Red Team, and researched supply-chain attacks at Outflank. I also run CyberPloeg, working on penetration testing and web development.
View my experienceWeb development
My roots are in back-end development. I build web applications with Laravel and PHP, with experience delivering and maintaining software for clients at SMIT.
- Laravel
- PHP
- JavaScript
- Python
Offensive security
I find and responsibly report vulnerabilities, research attack techniques, and turn findings into actionable reports. My experience includes KPN's Red Team and graduation research at Outflank.
- Penetration testing
- Red teaming
- Responsible disclosure
- CTFs
Outside project work, I keep learning through CTFs, Hack The Box, and TryHackMe.
Experience &
research
Work, education, disclosures, and competitions alongside my studies.
Jump to contact-
Sep 2026
First place at National Hackers Cup 2026
Won the first National Hackers Cup with Team Trencryption, alongside Paul Stokreef, Hamza Koyuer and Nali Chaushli. Our team took home the NHC trophy and €2,000 in prize money, earning the title of best hacker team in the Netherlands.
View linkedin announcement -
2026
Cyberbootcamp 2026
Took part in Challenge The Cyber's 2026 bootcamp, continuing to train, compete and grow alongside the Dutch cybersecurity community.
Challenge the Cyber -
9 Jul 2026
Graduated cum laude
Completed the HBO-ICT programme at the Amsterdam University of Applied Sciences with distinction, specialising in cybersecurity.
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Feb – 19 Jun 2026
Supply-chain research at Outflank
Completed a graduation internship at Outflank Security Tooling, researching a controlled, ethical simulation of package-based supply-chain attacks from a red-team perspective.
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7 – 13 Jul 2025
Second place in L3akCTF 2025
Returned to Challenge The Cyber's 2025 bootcamp for hands-on labs and CTFs. With Team Superflat, placed second out of 1,587 teams in L3akCTF 2025.
Cyberbootcamp -
Dec 2024 – now
Founded CyberPloeg
Launched my own cybersecurity company, bringing together two things I enjoy most: web development and penetration testing.
Visit CyberPloeg -
Nov 2024
IP camera vulnerability · CVE-2024-51362
Co-discovered a vulnerability in an LSC Smart Connect Indoor IP Camera with Patrick and Twan. The issue allowed unauthenticated access to a live RTSP feed.
CVE record -
2024
Two award categories at HALON 2024
Placed with Team Reloading at SURF's HALON CTF in both the "Most Advanced Verified Vulnerability" and "Most Verified Vulnerabilities at Most Targets" categories.
Results -
Feb 2024
Recognition from the Dutch public sector
Responsibly disclosed vulnerabilities to both organisations: the Dutch Government recognised the finding with a T-shirt, while the Dutch Tax Administration awarded a Hall of Fame mention and trophy.
Hall of fame -
Feb – Jun 2024
Red team internship at KPN
Interned with KPN's Red Team, gaining hands-on experience in offensive security testing and clear, actionable reporting.
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2023
Responsible disclosure at LUMC
Found and responsibly reported a data leak at Leiden University Medical Center (LUMC), receiving public recognition in its Hall of Fame.
Recognition -
2023
27 verified vulnerabilities at HALON
Competed in HALON 2023 with Twan Terstappen and Patrick Kuin, finding confirmed vulnerabilities across Dutch education organisations and receiving the "Most Vulnerabilities Found at Most Participating Organisations" award.
VIEW HALON HALL OF FAME -
10 – 16 Jul 2023
Cyberbootcamp 2023
Joined a week-long cybersecurity bootcamp alongside 26 other hackers, with workshops and sessions from organisations including NCSC-NL, Deloitte, DEFION, Chapter8 and Bureau Veritas.
Cyberbootcamp -
2022 – 2023
First responsible disclosure
Reported a security issue to the Amsterdam University of Applied Sciences during my first study year and earned a place in its responsible-disclosure Hall of Fame.
Hall of fame -
Aug 2022 – Jul 2026
Specialising in cybersecurity
Started the cybersecurity-focused HBO-ICT programme at the Amsterdam University of Applied Sciences, pairing a builder's perspective with ethical hacking.
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Sep 2021 – Feb 2024
Back-end developer at SMIT
Worked as a back-end developer at SMIT. Digitaal vakmanschap B.V., building, testing and maintaining web applications for real clients.
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2019 – 2022
A foundation in web development
Studied Media Development at Mediacollege Amsterdam, building the software and web-development fundamentals that later became a security mindset.
Community
SURF workshop
Delivered a SURF workshop showing blue teamers how red teamers think, test and attack.
CTFs & bootcamps
Regularly compete in CTFs and return to Challenge the Cyber bootcamps to keep skills sharp.
Get in touch
Have a web project, security challenge, or research idea? I'd like to hear about it.
Contact me on LinkedIn