TwelveSec has one of the most experienced penetration testing teams in Greece and the Balkan countries, while our network of associates extends across three regions; Europe, North America and the Middle East.

Our team is comprised of veteran security specialists, who have extensive experience in the field and have implemented a large
number of ICT security projects.


Koukouras Ioannis (CISSP, CISA, CISM, OSCP, CISSP-ISSAP) is the Managing Director of TwelveSec



Yiannis has over 10 years of experience in the ICT domain, specialising in the Information Security sector. He started his career as a network security administrator and member of the CERT team at the Corps of Computing and research of the Hellenic Army. He then went on to offer consulting services for information security to various companies across the globe, gaining valuable, hands-on experience. Yiannis has partnered with some of the leading Information Security companies in the EMEA region and has accrued experience in working across different regions and industries, both on the field of security management and information security assurance.

Responding to the opportunities presented by the growth of the ICT sector in the EMEA region, Yiannis founded TwelveSec in order to bring together a team of seasoned pen-testers and security consultants that share the same passion for innovation and attention to detail. Yiannis is dedicated to leading TwelveSec to become one of the top Information Security firms on a global level.

His academic qualifications include a BEng in Electronic Engineering from the University of Lancaster and an MSc in Computer Systems Security from Glamorgan University, Wales. He also was the coach of the Greek National CyberSecurity Team for the European Cyber Security Challenge 2016. Yiannis holds some of the most widely acclaimed certifications in the industry, such as CISSP, CISA, CISM, and OSCP. Finally, Yiannis is an affiliate and member of ISACA, (ISC)2, and OWASP.

George Karagiannidis (OSCP, CISSP, CISA) is the Chief Operations Officer of TwelveSec



George is a Senior Information Security Consultant at TwelveSec. George is a seasoned pen-tester, having accumulated a wealth of experience from performing, as well as leading, Information Security projects that range from System/Network/Web Application Penetration Tests to Reverse Engineering, Security Design and Architecture
of critical Information Systems, and Information Security Management System (ISMS) implementation.

George has been involved in Information Security projects across different industries, including major Greek and Middle-Eastern banks, Telecoms providers, the European Commission and the US Health sector. He is interested in all the latest developments in the security industry, keeping pace with the latest cutting-edge technologies and techniques that allow him to find innovative solutions to the complex puzzles posed by the ever-evolving ICT sector.

Takis Krommydakis (CISM, CISA, CRISC, C|EH, SOTP, IT/IL v3 (F), ISO27k LA/A, CSSLP, CISSP) is a senior Security Consultant at TwelveSec



Takis is a goal-oriented and achievement-focused IT and Information Security professional, with 15 years of experience in the industry. He possesses deep technical knowledge, with a background in infrastructure and application penetration testing, he has deep knowledge of the Windows, Unix, Linux operating systems and is
well-versed in multiple programming/scripting languages.

He has implemented numerous International and European-wide security-focused projects, using his communication skills to onboard new clients, as well as secure ongoing business from existing, high-profile clients. Managing full-lifecycle of projects, from initiating client engagement to delivering final reports, his keen eye for detail is central to his success. With a clear focus on quality, he has been integral in driving quality improvements and securing quality standardization in the companies he has worked for.

Takis possesses expertise gained while working on large-scale European and International security projects, designing systems to optimize secure functioning, writing and executing security test cases,
and conducting penetration and vulnerability testing.

Panayiotis Yialouris is an Information Security Consultant at TwelveSec



Panagiotis is a security consultant with more than six years of both academic and professional experience in the Information Security industry. He holds a B.Sc. degree in Informatics from the University of Piraeus and an M.Sc. degree in Computer Security from the University of Birmingham. His prior working experience includes the Cyber Defense department of the Hellenic Army, as well as various IT roles in the Research and Healthcare industries.

Panagiotis possesses solid technical expertise in many different aspects of Information Security. He has participated in a number of InfoSec projects in Greece as well as in the UK, ranging across Penetration Testing, Malware Analysis, Security Analytics, Security Management and more.

Xenofon Vassilakopoulos (OSCP), is an Information Security Consultant at TwelveSec



Xenofon Vassilakopoulos is a Security Consultant with more than six years of both academic and professional experience.

He holds a higher degree (B.Tech) from the Department of Informatics Engineering at the Technological Educational Institute of Central Macedonia and a Master’s Degree (M.Sc) in Information Security from the Department of Digital Systems at the University of Piraeus.

Xenofon has worked in both the private and public sectors as a freelancer, having accumulated experience as a Software Developer, Systems Administrator, and Security Engineer. He possesses a wealth of technical knowledge, with a background in security systems infrastructure. He has deep knowledge of the Windows, Unix, and Linux operating systems as well as multiple programming/scripting languages and is an official contributor to the OWASP Security Knowledge Framework.

Xenofon’s professional experience is based on a number of security projects specifically in Banking Sector. He has also conducted security research in CyberSecurity and Malware Analysis, examining Security Analytics methods for advanced threats.

George Koukoumpedakis is an Information Security Consultant at TwelveSec (Photo)



George is a programmer and an ex-web developer, who had always been interested in pen testing before finally making the decision to pursue a career in information security. He has worked using various platforms and programming languages and is now eager to explore the world of security firsthand. Although he still has limited experience within the sector, his solid technical background has allowed him to catch up with all the latest developments and best practices.

He holds a diploma of Electronic and Computer Engineering from the Technical University of Crete, and his interests include penetration testing, reverse engineering, mobile app security and IoT.

George Karpouzas is an Information Security Consultant at TwelveSec (Photo)



George is a Security Consultant, Penetration Tester, Malware Researcher and Social Engineer with more than 8 years of professional experience.

George has over 15 years of experience in Software Programming. He was writing code even before he made it into Athens University of Economics and Business, Computer science department.

He has over 15 years of experience in Security Researching. He is interested in Red Teaming, Malware, Kernel development, IT Security and more.

Phil Kaloheretis is a Business Development Manager at TwelveSec (Photo)


Phil is a business development manager in the TwelveSec team. He is a technology enthusiast with experience in innovation procedures, having been involved in several Greek & European Research projects for more than 7 years in the biggest research center of Greece.

In TwelveSec he is involved with Research & Innovation Projects and when he is not, he tries to find ways to help the company grow.

He holds a BSc in Sociology and a Master in Business Administration.