Senior Penetration Tester

JR United Kingdom; Colchester; On-site; GBP 60,000 - 90,000; Full time

Job summary

A top cyber consultancy is seeking a Senior Penetration Tester in Colchester for high-impact penetration testing and red teaming engagements. The role requires technical expertise in security assessments and mentoring junior testers while employing frameworks like MITRE ATT&CK. Join an elite team to enhance security strategies for diverse clients.

Qualifications

• Proven experience in penetration testing and red teaming.
• Strong understanding of attacker TTPs and detection evasion.
• Familiarity with frameworks like OWASP, MITRE ATT&CK, and NIST.

Responsibilities

• Lead and execute complex penetration tests and adversary simulations.
• Deliver red team engagements aligned with frameworks such as TIBER and CBEST.
• Create detailed technical and executive reports for clients.

Skills

Penetration Testing

Red Teaming

Threat Analysis

Technical Reporting

Continuous Learning

Education

OSCP

CRTO

OSEP

CREST CRT

Tools

Cobalt Strike

PoshC2

Sliver

Job description

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Opus are looking for an experienced Penetration Tester to join our client, a cyber consultancy specialising exclusively in penetration testing and red teaming, delivering high-impact, adversary-simulated engagements for clients ranging from agile tech scale-ups to critical infrastructure providers. As a Senior Penetration Tester, you’ll play a central role in executing and shaping these engagements—across infrastructure, web, cloud, and bespoke environments—while also leading goal-based assessments and full-scale red team operations.

This is a hands-on, client-facing position suited to someone who thrives in technically demanding scenarios and wants to work alongside a small, elite team of offensive security specialists.

Key Responsibilities

• Lead and execute complex penetration tests and adversary simulations
• Deliver red team engagements aligned with frameworks like TIBER, CBEST, and MITRE ATT&CK
• Develop custom tooling and exploits where required
• Create detailed, client-facing technical and executive reports
• Mentor junior testers and contribute to internal R&D
• Stay sharp: engage in continuous learning and threat landscape analysis

About You

• Proven experience in penetration testing and red teaming (internal, external, app, cloud, etc.)
• Strong understanding of attacker TTPs and detection evasion
• Familiarity with frameworks such as OWASP, MITRE ATT&CK, and NIST
• Experience with C2 frameworks (e.g., Cobalt Strike, PoshC2, Sliver)
• Certifications such as OSCP, CRTO, OSEP, or CREST CRT preferred (but not required)