Penetration Tester – SC Cleared, Defence & Security Focus

Thales Group; Doncaster; On-site; GBP 66,000 - 106,000; Full time

Benefits offered by this job

Performance-related bonus

Half day Fridays

28 days annual leave + bank holidays

Paid volunteering 24 hours

Private healthcare

Pension scheme

Life cover

Employee Assistance Program

Mental wellbeing app access

Employee discounts

Gym membership discounts

Job summary

Thales Group in the United Kingdom is seeking a hands-on penetration tester to cover Windows, Linux, mobile, web, and cloud environments. You will identify vulnerabilities, produce clear reports, and support high-security accreditation programmes.

The role requires CSTL certification and a strong grasp of testing methodologies, with a pathway toward technical leadership. UK national with SC clearance is required.

Qualifications

• Hands-on penetration testing across IT and/or OT environments.
• Degree in Computer Science, Engineering, or equivalent experience.
• Strong understanding of security testing methodologies and frameworks.
• Experience producing clear, actionable technical reports.
• Industry certifications such as CREST, OSCP, CEH, GPEN, GXPN desirable.
• Background in Defence, Aerospace, Government, Nuclear, Transport or other regulated industries desirable.
• Familiarity with compliance-driven environments and secure system accreditation desirable.
• UK National and ability to obtain Security Clearance (SC) without caveats.

Responsibilities

• 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 cybersecurity SMEs across projects and stay 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

Security reporting

Security frameworks

Stakeholder collaboration

Secure operating procedures

Education

Bachelor's degree in Computer Science, Engineering, or equivalent

Tools

Android

iOS

Linux

Windows

Cloud

Web

Job description

Thales Group in the United Kingdom is seeking a hands-on penetration tester to cover Windows, Linux, mobile, web, and cloud environments. You will identify vulnerabilities, produce clear reports, and support high-security accreditation programmes.

The role requires CSTL certification and a strong grasp of testing methodologies, with a pathway toward technical leadership. UK national with SC clearance is required.