Senior Penetration Tester

JR United Kingdom; Ipswich; On-site; GBP 50,000 - 85,000; Full time

Job summary

A leading cyber consultancy is seeking an experienced Senior Penetration Tester to join their elite team focused on high-impact security assessments. The role entails executing and shaping penetration tests across diverse environments, mentoring junior team members, and contributing to ongoing threat analysis.

Qualifications

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

Responsibilities

• Lead and execute complex penetration tests and adversary simulations.
• Deliver red team engagements aligned with frameworks like TIBER, CBEST, and MITRE ATT&CK.
• Mentor junior testers and contribute to internal R&D.

Skills

Penetration testing

Red teaming

Threat analysis

Technical report writing

Education

Certifications such as OSCP, CRTO, OSEP, or 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)