Penetration Tester (Infrastructure)

ZipRecruiter; London; Hybrid; GBP 70,000 - 100,000; Full time

Job summary

A leading company is seeking an experienced Infrastructure Penetration Tester for a hybrid role based in London. This hands-on position involves conducting critical assessments in sensitive environments, requiring strong technical skills and experience in delivering concise reporting. Ideal candidates must be eligible for UK Security Clearance and be proficient at navigating complex systems independently.

Qualifications

• At least 4 years’ experience in infrastructure penetration testing.
• Strong knowledge of Active Directory exploitation techniques.
• Confident working in high-stakes, sensitive environments.

Responsibilities

• Conduct internal infrastructure and Active Directory penetration tests.
• Produce clear, concise reports for technical and non-technical audiences.
• Contribute to the evolution of internal tooling and testing methodologies.

Skills

Infrastructure Penetration Testing

Active Directory Exploitation Techniques

Command-line Skills (Windows and Linux)

Legacy Systems Handling

Technical Debt Management

Tools

Penetration Testing Tools

Scripting (Python)

Job description

Job Description

Penetration Tester – Infrastructure

Salary: £70,000–£100,000 (depending on experience)

Location: Hybrid – London (2 days per week on-site)

Note: To be eligible for this role, you must be eligible for UK Security Clearance (SC).

A high-performing digital security team is looking for an experienced Infrastructure Penetration Tester to join them in delivering critical assessments across complex and sensitive client environments.

This is a hands-on internal testing role, not web application focused, where you'll be expected to work independently and navigate challenging systems with confidence.

This role is suited to testers who thrive in technically demanding scenarios, want autonomy, and are motivated by work with real-world impact.

Key Responsibilities

• Conduct internal infrastructure and Active Directory penetration tests in live production environments
• Produce clear, concise reports tailored to both technical and non-technical audiences
• Build trusted relationships with clients in a consultancy-facing capacity
• Work within a small, high-trust team on sensitive engagements
• Contribute to the evolution of internal tooling and testing methodologies
• Operate effectively in environments with limited documentation or predefined processes

Essential Experience and Skills

• At least 4 years’ experience in infrastructure penetration testing
• Strong knowledge of Active Directory exploitation techniques (privilege escalation, lateral movement, etc.)
• Confident working in high-stakes, sensitive environments
• Strong command-line skills across Windows and Linux systems
• Ability to work through legacy systems, unpatched software, and environments with technical debt

Desirable Skills

• Python scripting or automation experience
• Understanding of Operational Technology (OT) networks
• Familiarity with internal infrastructure exploitation tools

Certifications ( but not essential):

• CREST CTM, CTL, CSTM or Cyber Scheme Practitioner
• OSCP (current or lapsed)

If you’re an experienced infrastructure penetration tester looking for meaningful work, we want to hear from you.