members

Originally from Estonia, Lauri spent eight years as a Linux administrator at Tallinn University of Technology, where he built deep technical expertise in networking, Linux systems, and complex security environments.

In 2003, he cleared the "hacking mission" of Zone-H, a European security research organization known for tracking website defacements, faster than anyone before him, and went on to become one of its core members, teaching hands-on hacking seminars around the world.

At Cyber Defense Institute, he has built an impressive track record, including penetration testing engagements for numerous major Japanese corporations and reaching the finals of the DEF CON CTF competition. Beyond his exceptional hacking skills, he is fluent in Estonian, English, Japanese, Russian, and Finnish.

Lauri Korts-Pärn

CTO

True to his title of Chief Hacking Officer, he commands an offensive skill set unmatched even among Cyber Defense Institute's already formidable roster of hackers. He stands at the very top of the pyramid the living embodiment of CDI's offensive capabilities.

His sense for attack, technical skill, speed, and knowledge are all exceptional, and he has no blind spots when it comes to hacking targets, whether web, network, embedded devices, control systems, or even people.

He's been hacking as naturally as breathing since the dawn of the internet, once making his home in corners of the underground world best left undiscussed, before eventually joining Cyber Defense Institute to help protect the peace of the galaxy. In an earlier chapter of his career, he also once played his part in the global economy — via a hefty international phone bill from the Seychelles.

Shingo Hayashi

CHO

A security engineer through and through who loves web application testing and calls it his true calling. He has worked in penetration testing for over 20 years and has led large-scale engagements, including testing for critical infrastructure systems.

He has a track record of discovering vulnerabilities in a wide range of software and web services, including browsers and router products, with more than 10 CVEs published under his name. His passion for security testing extends beyond his day job; he also contributes to public safety through bug bounty hunting as a hobby.

He holds certifications including CISSP, OSCP, BSCP (Burp Suite Certified Practitioner), Registered Information Security Specialist (Japan's national cybersecurity certification, registration No. 009597), and Technical Engineer (Network, Database, Security), a former category of Japan's national IT certification system that has since been reorganized into the current examination structure.

Noriaki Iwasaki

Offensive Security Group
Principal Security Engineer

A "binarian" since birth, and a true expert in malware analysis. At Cyber Defense Institute, he handles malware analysis, related threat analysis, and binary-focused assessments as part of the company's incident response and forensic investigation work.

Known by the handle "ucq," he has competed in CTF competitions around the world, including past championship wins. His research presentation on Stuxnet at CodeGate, an international security conference held in South Korea, earned high praise from security engineers worldwide.

His activities extend widely, including serving as a lecturer for Security Camp (a competitive, government-backed cybersecurity training program for young talent in Japan, organized by IPA), speaking internationally, and appearing in media.

Hayato Ushimaru

Low‑Layer Security Group
Binarian

Serves as Tech Lead within the Low-Layer Security Group at Cyber Defense Institute, handling both team management and business development. Since joining the company as a new graduate in 2015, he has expanded his expertise across web application testing, network penetration testing, and embedded device/IoT security assessments.

In penetration testing engagements in particular, he plays what the team jokingly calls its "first one through the door," the member who follows his curiosity to break into targets ahead of everyone else, while also contributing to the wider community by reporting newly discovered vulnerabilities to IPA and affected vendors.

He also gives back technical knowledge through conference talks, having spoken at m0leCon, Security.Tokyo, AVTOKYO, and CODE BLUE (U-24).

Hiroki Matsukuma

Low‑Layer Security Group
Tech Lead

Works on malware analysis, threat research, and threat intelligence product development at Cyber Defense Institute. He is a specialist in malware analysis, with particular expertise in reverse engineering malicious software.

In the field of threat intelligence, he tracks the latest APT (Advanced Persistent Threat) activity and has presented his research at numerous conferences in Japan and abroad, including JSAC (JPCERT/CC's Japan Security Analyst Conference), Virus Bulletin, HITCON, AVAR, Black Hat Arsenal, and CODE BLUE. He applies this expertise to the development of practical threat intelligence products.

He is also active in the broader security community, writing technical books, giving talks, contributing to open-source projects, and lecturing at Security Camp to help train the next generation of security talent. Or so the story goes; his true identity remains a secret.

Shota Nakajima

Threat Intelligence Group
Tech Lead

After building his career as a support engineer, at a systems integrator, and as a security engineer, he made the move to Cyber Defense Institute, driven by a deep curiosity about the underlying mechanisms of IT technology. Since joining, he has focused mainly on network-related penetration testing, applying low-level technical skills he developed through self-study across a wide range of engagements, including Threat-Led Penetration Testing (TLPT), red team exercises, breach assessments, and incident response for ransomware attacks.

He is especially known for his deep expertise in C/C++, and his catchphrases, "I want to write every program in C/C++" and "I want to become a CPU," say it all. He holds OSCP, OSEP, and OSEE certifications.

Yu Niida

Offensive Security Group
Senior Security Engineer

Joined Cyber Defense Institute after working as a systems engineer and programmer. Over his 10 years at CDI, he has worked on penetration testing engagements for private companies, government and public-sector clients, and critical infrastructure. Drawing on his expertise as a network hacking specialist, he has also taken part in forensic and breach investigation projects, given talks on critical infrastructure security, and served as a technical advisor for a TV drama, among his many other activities.

He has a disciplined, stoic personality and is constantly working to improve his own skills. In recent years, his pursuits have extended beyond honing his cybersecurity expertise to include a passion for mountain climbing.

He holds certifications including CISSP, OSCP, OSCE, OSWP, and Microsoft Cybersecurity Architect Expert.

Satoshi Horikoshi

General Manager, Technology Division

Discovered his passion for electronics while repairing an old motorcycle, which set him on a path toward hands-on hacking.

In his previous role, he developed embedded devices; at Cyber Defense Institute, he conducts penetration testing across a wide range of devices, including industrial equipment, automotive systems, IoT devices, medical devices, and consumer electronics. Outside of work, he spends his nights modifying vehicles in his garage and tending vegetables in his garden as a self-proclaimed "International Class-A Farmer."

He holds certifications including Registered Information Security Specialist (registration No. 003499), Network Specialist, IPC-7711/21 (Rework, Modification, and Repair of Electronic Assemblies), and a Class 2 Electrician's License (Japan).

Yuta Teshima

Low-Layer Security Group

Joined Cyber Defense Institute after spending 10 years in academia, and is known by the nickname "Security Accelerator."

He specializes in penetration testing that involves physically modifying or reworking hardware, is highly knowledgeable in wireless communications, and has recently been developing hacking tools as well.

He served as a lecturer at the Security Camp National Convention from 2020 to 2025, and holds a Ph.D. in Science. His certifications include Registered Information Security Specialist (registration No. 001410), First-Class Radio Engineer (Land), First-Class Radiotelephone Operator (Maritime), and Aeronautical Radiotelephone Operator, all national radio operator licenses issued in Japan, as well as IPC-7711/21 (Rework, Modification, and Repair of Electronic Assemblies).

Keisuke Nakao

Low-Layer Security Group
Tech Lead

Spent more than 10 years developing web applications and software before witnessing a hacking incident affecting a service he personally used, which prompted his decision to switch careers into cybersecurity.

He gained experience as a cybersecurity engineer at a financial institution in Sweden before joining Cyber Defense Institute.He currently conducts network penetration testing and red team exercises for private-sector clients, contributes to service development, and helps train the next generation of international security talent.In his personal time, he has also been studying martial arts and Kampo, Japan's traditional system of herbal medicine.

He holds OSCP, CRTO, CRTL, CRTE, and GPEN certifications.

Andreas Persson

Offensive Security Group
Senior Security Engineer

Joined Cyber Defense Institute as a new graduate in 2017. After working on web application testing, device assessments, and network penetration testing, he now works within the Low-Layer Security Group.

He has contributed to the INTERPOL Digital Security Challenge (a cybercrime investigation training exercise developed for INTERPOL) and to the development of an online learning service for training security engineers. He competed in the CODEGATE CTF 2024 Finals.

Outside of work, alongside road cycling and DJing, he is deeply passionate about bowling, so much so that his shoe closet at home overflows with bowling balls. His High Game (his best single-game score) is 300, a perfect game, and his specialty is picking up the 7–10 split, one of the most difficult shots in the sport. He's not kidding around.

Hayato Niibo

Low-Layer Security Group

Head of the SRE (Site Reliability Engineering) department. Joined Cyber Defense Institute after working as a security engineer and network engineer at a major domestic ISP. He is a true full-stack engineer, with expertise spanning backend systems, networking, and infrastructure, from development through operations.

At Cyber Defense Institute, he leads the design and operation of mission-critical infrastructure that underpins the company's technical capabilities, including a threat intelligence collection system, a forensic system for large-scale networks, and an OSINT platform.

He is rumored to know more about the restaurants around Ochanomizu and Jimbocho than anyone else in Chiyoda Ward, and spends his weekends staying properly "hydrated" with beer and sake while strength training to keep body and mind in shape.

Masaya Ishizuka

Head of SRE (Site Reliability Engineering)

Spent 24 years working on ICS/SCADA system development for critical infrastructure, with experience in network design and construction, systems integration, and middleware development, and led security design, risk analysis, and countermeasure development for large-scale SCADA systems.

In 2019, he joined Cyber Defense Institute to bring an attacker's perspective back into the industrial control systems field. He has worked on penetration testing engagements involving critical infrastructure and systems related to the Tokyo Olympics, bringing both a defender's and an attacker's point of view to his work.

He places great importance on proposing security measures that operational teams can genuinely accept and act on, and shares practical insights, from proprietary protocol analysis to test-environment construction and monitoring tool evaluation, through blog posts and conference talks. He holds a Registered Information Security Specialist certification (registration No. 018991), a Network Specialist certification, and OSCP+.

Koji Yasui

Offensive Security Group
Principal Consultant

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