Penetration Tester - Vulnerability Researcher

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)
CSTL (Cyber Scheme Team Leader) certification is a must 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 13:0028 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 scheme

Life cover
24/7 Employee Assistance Program and access to mental wellbeing app Employee discount shopping schemes on major brands and retailers

Gym membership discounts

Security Clearance Requirement:

Due to the nature of the work that we do at Thales, many of our roles are subject to security restrictions. This role requires you to be a UK National and achieve Security Clearance (SC) without any caveats. It would be advantageous if currently held, however, if not currently held, it is a requirement that the successful applicant undergo, achieve, and maintain SC Clearance prior to commencing employment.

If approved by the MOD, a dual national from a non-ITAR country may be considered. To be eligible for full SC, you generally need to have resided in the UK for the last 5 years. In some circumstances, a minimum of 3 years’ residence in the UK over the last 5…