Overview
We are seeking an experienced Senior Penetration Tester with a strong background in infrastructure security testing to join a growing offensive security team. The ideal candidate will have deep technical expertise, the ability to lead and independently deliver complex engagements, and a passion for uncovering and exploiting vulnerabilities across enterprise environments. You will play a key role in strengthening the organisation's security posture by conducting infrastructure–focused assessments, mentoring junior testers, and influencing remediation strategies.
Key Responsibilities
* Deliver internal and external network and infrastructure penetration tests, including on–premises and cloud–hosted environments
* Perform testing of Windows & Linux infrastructure, Active Directory, network services, and security appliances
* Conduct vulnerability exploitation, privilege escalation, and lateral movement to demonstrate full attack paths
* Lead small engagement teams and oversee delivery quality, documentation, and client communication
* Produce high–quality, concise, and risk–aligned reports with actionable remediation guidance
* Support scoping calls, stakeholder workshops, and post–engagement debriefs
* Contribute to tooling, methodology enhancement, and internal research initiatives
* Stay up–to–date with emerging vulnerabilities, exploits, and attacker techniques
Required Skills & Experience
* 3–5+ years' professional penetration testing/offensive security experience
* Strong understanding of enterprise infrastructure, AD security, networking, and protocols
* Proficiency with tools such as Nmap, Nessus, Metasploit, BloodHound, Burp Suite, Kali/Linux toolsets
* Solid track record of delivering infrastructure pentests end–to–end
* Excellent communication skills, including producing business–focused reporting
Preferred Qualifications
* CHECK Team Member (CSTM) or CHECK Team Leader (CTL)
* CREST CRT/CCT, OSCP, OSEP, or equivalent recognised industry certifications
* Experience in cloud infrastructure testing (Azure/AWS), desirable but not essential
* SC or DV clearance beneficial (or eligibility to obtain it)
What We Offer
* Salary up to GBP80,000 depending on experience + performance bonus
* Strong personal development support – certifications funded and continuous training
* Defined career progression into CTL or Red Team positions
* Hybrid working with London as the preferred base
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