Cybersecurity Penetration Tester in London

Location: Remote UK, United Kingdom

Thales people architect identity management and data protection solutions at the heart of digital security. Business and governments rely on us to bring trust to the billions of digital interactions they have with people. Our technologies and services help banks exchange funds, people cross borders, energy become smarter and much more. More than 30,000 organizations already rely on us to verify the identities of people and things, grant access to digital services, analyze vast quantities of information and encrypt data to make the connected world more secure.

Together we offer fantastic opportunities for committed employees to learn and develop their career with us. At Thales UK, we research, develop, and supply technology and services that impact the lives of millions of people each day to make life better, and keep us safer. We innovate across the major industries of Aerospace, Defence, Security and Space. Your health and well-being matters to us and that's why we offer you the flexibility to do what's important to you; whether that's part time hours, job sharing, home working, or the ability to flex your start and finish times. Where possible, we support a working pattern that suits your lifestyle and helps you reach your ambitions.

Join a team where red teaming meets real impact - safeguarding defence platforms that shape national security!

• Safeguard UK Defence systems through advanced penetration testing and red teaming on critical military platforms
• Tackle complex threat simulations and exploit development across IT, OT, cloud, and embedded environments
• Use cutting‐edge tools with funded training and certifications (CHECK, CREST, OSCP, GIAC)
• A developmental role where you'll put your own stamp on future capability

We are seeking a security‐cleared Penetration Tester to join our dynamic Cyber Security team, working at the forefront of UK Defence and national security. In this role, you'll take on advanced security testing, vulnerability assessments, and red team exercises across both classified and unclassified environments - directly strengthening the resilience of mission‐critical networks and applications.

This position offers the opportunity to apply your expertise in offensive security methodologies, secure system design, and the unique challenges of defence environments. While prior defence experience is highly valued, we also welcome applications from seasoned red team specialists and offensive security professionals from sectors such as utilities, nuclear, and automotive, who bring transferable skills and fresh perspectives to our mission.

The Thales product portfolio wouldn't exist without the core engineering specialities that are AI, Cyber and Human Factors. These future-focused skills play an essential role within the wider engineering organisation and provide great opportunities to work on cutting-edge technologies.

Cybersecurity and Digital Identity (CDI) - from secure software to biometrics and encryption, CDI GBU technologies and services enable businesses and governments to authenticate identities and protect data, so they stay safe and enable services in personal devices, connected objects, the cloud and in between. Cybersecurity Premium Services (CPS) supports its enterprise and government customers in the cybersecurity of their digital transformation. We contribute to the identification and control of cyber risks, ensure the implementation of best reduction practices, operate threat driven cyber incident detection and response services, and intervene with our clients when attacks materialise.

• Competitive salary and benefits package designed to support our employees' wellbeing and professional growth
• Annual bonus (VCP)
• Pension – match like-for-like up to 7% of annual base salary
• Life Assurance – 2 x base salary minimum (8 x salary if part of the pension scheme)
• Income Protection – 50% of salary less state benefits for 5 years
• Annual Leave – 201 hours, bank holidays, plus 1 company day
• Private Medical Insurance - Couples cover
• Half day every Friday, usually finishing around 1:00pm
• 24/7 Employee Assistance Programme
• 24 hours paid leave for volunteering activities
• Access to flexible benefits and discounts – dental insurance, buying & selling annual leave, cycle to work, and many more

• Lead end‐to‐end penetration testing across networks, applications, cloud infrastructures, and embedded systems - delivering actionable insights that strengthen mission‐critical environments
• Drive advanced vulnerability assessments and exploit development, executing post‐exploitation activities within authorised scopes to uncover hidden risks and resilience gaps
• Orchestrate red and purple team engagements, simulating sophisticated threat scenarios against defence systems to rigorously test and enhance security posture
• Produce high‐impact technical reports and executive briefings, translating complex findings into clear risk narratives, business impact assessments, and prioritised remediation strategies
• Partner with defensive operations and risk management teams to sharpen detection, accelerate response, and embed proactive resilience across the enterprise
• Stay ahead of adversaries by maintaining expert knowledge of tactics, techniques, and procedures (TTPs) employed by state and non‐state actors in the defence sector
• Advance security testing methodologies and tooling, contributing to innovative threat modelling approaches tailored for complex, high‐assurance environments
• Champion compliance and assurance by aligning practices with MOD, NCSC, and international standards (JSP 440, ISO 27001, NIST, CHECK, CREST), ensuring robust governance and trust

At Thales, we are committed to equal opportunities and welcome all talented individuals to consider joining our team. So even if you don't match every statement below but feel you have some of the experience, knowledge or skills needed for this role, we encourage you to apply. It will take all of us working together to deliver solutions to the world's most critical challenges.

• Degree in Computing, Cybersecurity, or a related field - or equivalent professional experience in lieu of formal tertiary studies
• CHECK Team Leader accreditation currently held
• Demonstrated track record as a Penetration Tester, Red Team Operator, or equivalent offensive security specialist
• Proven ability to manage small technical teams, demonstrating strong people skills, mentorship, and collaborative leadership
• Deep expertise in network protocols, application security, operating systems, and cloud platforms across both IT and OT environments
• Hands-on proficiency with industry-standard tools including Burp Suite, Metasploit, Cobalt Strike, Nmap, Nessus, plus custom scripting in Python, PowerShell, and Bash
• Proven experience conducting penetration tests across diverse systems: Windows, Linux, Android, iOS, Web Applications, and Cloud infrastructures
• Familiarity with defence and government environments, including secure handling of classified information
• Exceptional written and verbal communication skills, able to translate complex technical findings into clear, actionable insights
• SC or DV clearance (mandatory for project delivery), with eligibility or current holding

• Recognised certifications such as CREST (CPSA, CRT, CCT INF, CCT APP, CCRTS, CCRTM), CHECK Team Member/Leader, OSCP, OSCE3, CEH, or GIAC (GPEN, GWAPT, GRTP, GXPN)
• Exposure to ICS/SCADA, RF systems, or military-grade communication networks
• Strong grasp of Threat Intelligence