Penetration Tester

Company Description

Closed Door Security is an offensive security consultancy founded in 2021 and headquartered in the Outer Hebrides, Scotland. We provide penetration testing, threat-led assessments, and security assurance services to organisations that require a realistic understanding of their cyber risk.

As a CREST-accredited organisation and a certification body for the NCSC’s Cyber Essentials Plus scheme, our focus is on meaningful testing that reflects how attackers actually operate. We value clear thinking, strong technical fundamentals, and the ability to translate findings into practical, defensible security improvements.

Role Description

This is a full-time role with flexible remote working. It is well suited to a mid-level Penetration Tester who is comfortable working independently, can manage their own testing activities, and takes pride in producing clear, high-quality reports.

You will deliver penetration tests across networks, applications, and infrastructure, with exposure to scenario-based and threat-informed testing. While you may work alongside senior testers on more complex engagements, you will be expected to plan and execute standard tests end-to-end with minimal supervision.

A core part of the role is communicating findings effectively understanding not just what the vulnerability is, but why it matters, how it could realistically be exploited, and what practical steps should be taken to address it. You’ll work closely with teammates to review findings, improve testing approaches, and continue developing your technical and analytical skills.

Key Responsibilities

• Conduct penetration testing across networks, applications, and modern enterprise environments

• Apply critical thinking to identify realistic attack paths and business impact

• Produce clear, well-structured, client-ready reports

• Manage your own workload, timelines, and evidence collection

• Collaborate with team members to validate findings and improve testing quality

• Build an understanding of attacker behaviour relevant to client environments

Qualifications & Experience

• Practical experience in penetration testing or offensive security

• Strong understanding of common vulnerabilities, attack techniques, and testing methodologies

• Excellent written communication skills and attention to detail

• Ability to work independently and make sound technical judgements

• Analytical mindset with a focus on real-world outcomes

• Relevant certifications (e.g. OSCP, CREST, or similar) are beneficial but not essential

Eligibility

• Due to the nature of our work and associated security clearance requirements, this role is only open to people that could pass UK Security Clearance. If you are unsure what that means please check before you apply.