Application Security & Penetration Testing Company

Protect your data and apps in line with OWASP, PCI DSS, and ISO27001 requirements.

Get a free retest within 60 days.

Security Services

Application Security

Test your application for vulnerabilities and check the security of your software development.

Penetration Testing

Perform your security posture assessment by conducting infrastructure penetration testing.

Completed Projects

years in business

happy clients

successful projects

Why Berezha?


  • We focus on your business needs
  • The optimal value for your money
  • Discount for all repeated projects
  • Flexible, customer-centric project style
  • Actionable, context-driven reports


  • The team lead by top bug bounty hunters
  • Holding top industry certifications
  • Expertise in various technology stacks
  • Large bag of up-to-date hacker tricks
  • Adaptive, business-centric approach


  • Professional team of like-minded people
  • Always eager to get new knowledge
  • Always ready to share the knowledge
  • Involved in OWASP Kyiv & NoNameCon
  • Founded by the community leaders




More Info

The Offensive Security Certified Professional certification is a unique evaluation of offensive security skills based on a 24-hour hands-on exam that proves such areas of expertise as network penetration testing, vulnerability identification, and exploitation along with proper documentation and reporting of issues identified.



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A Certified Information Systems Security Professional certificate proves skills and experience needed to effectively design, implement and manage a best-in-class cybersecurity program, including risk management, architecture, communication, and network security, access management, security operations, and application security.



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The Certified Information Systems Auditor designation is a globally recognized certification for IS audit control, assurance, and security professionals. It proves audit experience, skills, and knowledge, and demonstrates the capability to assess vulnerabilities, report on compliance and institute controls within the enterprise.


They helped locate and resolve bugs in the client’s system, meeting the expectations of the internal team. Berezha Security collaborates effectively with the client. The team leverages its technical expertise to ensure a successful project.

Serhii Kokhan

Senior Security Engineer, Conductor

They did a good job and on output, we got reports with security-related issues missed by us. The reports thoroughly cover issues that stakeholders had previously missed. Their independent working style fostered a responsible work ethic.

Dmytro Vdovychynskyi

Security Engineer, Preply

Now, internal development teams are successfully implementing the skills they learned from Berezha Security. The specialists maintained an excellent communication style throughout the sessions.

Nazarii Uniiat

Security Engineer, Clario Tech Limited

Executive Team

Kos Korsun

Co-founder & Executive Director

More Info

As former deputy head of Cybercrime Division at Security Service of Ukraine, Kostyantyn was one of the founders and the first head of CERT-UA. After resigning from the service, Kos acted as Regional Director for the Ukrainian Research Office of iSIGHT Partners, an international cyber threat intelligence company. He was a co-founder and first Chairman of the Ukrainian Information Security Group and a long-term head of its UISGCON annual conference organization team.

Currently, Kos is active in the Ukrainian cybersecurity community and executes strategic leadership for Berezha Security.

Andriy Varusha


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Andriy is an accomplished manager with 10+ years of experience in various industry verticals. He has started his carrier in IT Audit and Consulting and continued in Enterprise IT and Software Development services. Andriy has experience of leading customer relationships within the US, UK, and Western Europe geographies, being responsible for distributed teams and permanent engagements of different scale.

Andriy has stood at the root of the Ukrainian cybersecurity professional community and has joined Berezha to advance his contribution to the development of the cybersecurity industry.

Vlad Styran

Co-founder & VP

More Info

Vlad is an internationally known cybersecurity expert with 15+ years of experience in Penetration Testing, security audits, and consulting. Vlad currently holds OSCP, CISSP, and CISA credentials and was certified as C|EH, ISO27001LA, and many more throughout his career. Vlad is a leader of the OWASP Kyiv chapter, a co-founder of the NoNameCon cybersecurity conference, and a speaker on the topics of Social Engineering threats and Penetration Testing methods and techniques.

At Berezha, Vlad is responsible for steady growth and building relationships with our customers.

+380 (44) 364 7336    +1 (315) 303 2323

6 Nimanska St., 41, Kyiv, Ukraine 01103

77 Sichovykh Striltsiv St., Kyiv, Ukraine