Penetration Tester - Vulnerability Researcher

Thales; West of England; On-site; GBP 60,000 - 90,000; Full time

Benefits offered by this job

Performance-related bonus

Half day Friday

28 days annual leave

Volunteer hours

Private healthcare

Pension scheme

Job summary

Thales in the United Kingdom is seeking a hands-on Penetration Tester to strengthen cyber security across IT and OT environments. You will conduct testing across Windows, Linux, mobile, web, and cloud, influencing secure design from early project stages.

You’ll produce clear technical reports, advise on risk-based controls, and collaborate with internal teams and customers on security improvements. The role offers the chance to work on mission-critical systems and grow into technical leadership.

Qualifications

• Hands-on penetration testing across IT and OT environments.
• Strong knowledge of security testing methodologies and frameworks.
• Experience producing actionable technical reports.
• Degree in Computer Science or Engineering.
• Industry certifications such as CREST, OSCP, CEH, GPEN, GXPN.

Responsibilities

• Conduct penetration testing across Windows, Linux, mobile (iOS/Android), web applications, and cloud environments.
• Identify, exploit, and clearly communicate security vulnerabilities and risks.
• Support accreditation and assurance activities on complex, high-security programmes.
• Advise on security controls and mitigation strategies aligned to customer needs.
• Contribute to governance frameworks, policies, and secure operating procedures.
• Produce high-quality technical reports and through-life security documentation.
• Act as a cybersecurity SME across projects, staying aligned with evolving regulations and standards.
• Collaborate with internal teams, customers, and external stakeholders at all levels.
• Support bid activities, including technical input and effort estimation.

Skills

Penetration testing

IT/OT security

Security reporting

Degree in CS/Engineering

CREST

OSCP

CEH

GPEN

GXPN

Education

Bachelor's degree in Computer Science or Engineering

Job description

Location: Crawley, United Kingdom

Thales is a global technology leader with more than 83,000 employees on five continents. With over 7,500 people in the UK, operating across defence, space, aerospace, and digital security, we help build a future we can all trust. Thales supports the security and stability of our nation by providing extraordinary technology to our customers, as well as delivering social value to the UK with our products and services.

Join Thales at a pivotal time as we expand our Cyber Security capability across critical national infrastructure, defence, and aerospace programmes. As a Penetration Tester, you’ll play a key role in identifying vulnerabilities across complex systems and helping secure technologies that truly matter.

From secure software to biometrics and encryption, our CDI technologies and services enable organisations to confidently authenticate identities and protect data with care and precision. We support businesses and governments in keeping people safe and enabling trusted services across personal devices, connected objects, the cloud and everything in between.

The Opportunity

You’ll work on high-impact projects, performing penetration testing across IT and OT environments while influencing secure design and risk mitigation strategies from early project stages through to delivery.

What You’ll Be Doing

• Conduct penetration testing across Windows, Linux, mobile (iOS/Android), web applications, and cloud environments
• Identify, exploit, and clearly communicate security vulnerabilities and risks
• Support accreditation and assurance activities on complex, high-security programmes
• Advise on security controls and mitigation strategies aligned to customer needs
• Contribute to governance frameworks, policies, and secure operating procedures
• Produce high-quality technical reports and through-life security documentation
• Act as a cybersecurity SME across projects, staying aligned with evolving regulations and standards
• Collaborate with internal teams, customers, and external stakeholders at all levels
• Support bid activities, including technical input and effort estimation

What We’re Looking For

• Hands‑on penetration testing experience across diverse platforms (IT and/or OT environments)
• Strong understanding of security testing methodologies and frameworks
• Experience producing clear, actionable technical reports
• Degree in Computer Science, Engineering, or equivalent experience
• Industry certifications such as CREST, OSCP, CEH, GPEN, GXPN (or similar)

Desirable Experience

• Background in Defence, Aerospace, Government, Nuclear, Transport, or other regulated industries
• Familiarity with compliance‑driven environments and secure system accreditation

Why Thales?

• Work on mission‑critical systems that protect national security and infrastructure
• Opportunities to move across domains, technologies, and international locations
• Clear pathways into technical leadership or people management
• Be part of a globally recognised engineering and technology organisation

Benefits

• Performance‑related bonus
• Half day every Friday, usually finishing around 13:00
• 28 days annual leave (plus bank holidays) with opportunity to buy up to 40 hours/year (pro rata)
• 24 hours volunteering paid for
• Private healthcare
• Pension schemelift?