Cybersecurity Penetration Tester

Thales; United Kingdom; Remote; GBP 50,000 - 80,000; Full time

Job summary

A leading cybersecurity firm in the UK is seeking an experienced Cybersecurity Penetration Tester to conduct advanced penetration testing and vulnerability assessments. The ideal candidate will have strong expertise in offensive security methodologies and the opportunity to make a national impact in UK Defence. This role offers competitive benefits, including an annual bonus and flexible working options.

Benefits

Annual bonus

Pension matching up to 7%

Private Medical Insurance

Flexibility in working hours

Employee Assistance Programme

Qualifications

• Degree in Computing, Cybersecurity, or a related field, or equivalent experience.
• CHECK Team Leader accreditation.
• Track record as a Penetration Tester or equivalent.

Responsibilities

• Lead penetration testing across networks, applications, and cloud infrastructures.
• Conduct vulnerability assessments and exploit development.
• Produce technical reports and risk narratives.

Skills

Penetration Testing

Red Team Operations

Offensive Security

Network Protocols

Application Security

Python scripting

Communication skills

Education

Degree in Computing, Cybersecurity, or related field

Tools

Burp Suite

Metasploit

Cobalt Strike

Nmap

Nessus

Job description

Cybersecurity Penetration Tester

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 is 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.

What the role has to offer

• 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

Our Opportunity

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.

What we offer you

• Annual bonus (VCP)
• Pension – match like‑for‑like up to 7% of annual base salary
• Life Assurance – 2 × base salary minimum (8 × 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 1:00 pm
• 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

Key Responsibilities and Tasks

• 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

About You

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.

Essential

• 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 specialistProven 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

Desirable

• 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 IC/S/SCADA, RF systems, or military‑grade communication networks
• Strong grasp of Threat Intelligence, MITRE ATT&CK framework, and adversary emulation techniques
• Previous involvement in projects supporting the MOD, defence primes, or critical national infrastructure (CNI)
• Domain expertise across Defence, Nuclear, Government, Aerospace, CNI, and Transport sectors

Step into a role where your expertise makes a national impact – join us today!

UKEO (UK Eyes Only)

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.

Please visit the UKSV website for further guidance:
https://www.gov.uk/government/publications/united-kingdom-security-vetting-clearance-levels/national-security-vetting-clearance-levels.

To be eligible for full SC, you generally need to have resided in the UK for the last five years. In some circumstances, a minimum of three years’ residence in the UK over the last five years may be accepted, with additional overseas checks.

#LI-VG1

In line with Thales’ Baseline Security requirements, candidates will be asked to provide evidence of identity, eligibility to work in the UK and employment and/or education history for up to three years. Some vacancies may require full Security Clearance which can require further evidence to be provided. For further details of the evidence required to apply for Baseline and Security Clearance please refer to the Defence Business Services National Security Vetting (DBS NSV) Agency.

At Thales we provide CAREERS and not only jobs. With Thales employing 80,000 employees in 68 countries our mobility policy enables thousands of employees each year to develop their careers at home and abroad, in their existing areas of expertise or by branching out into new fields. Together we believe that embracing flexibility is a smarter way of working.

Thales UK is committed to providing an inclusive and barrier‑free recruitment process. We will provide reasonable adjustments and support to ensure neuro‑diverse applicants or those with a disability or long‑term condition can be their best during the recruitment process. To request an adjustment, if you need this job advert in an alternative format or if you have any questions about the recruitment process, please contact Resourcing Ops for mid to senior roles, or the Early Careers Team for graduate and apprentice roles.

Great journeys start here, apply now!