Senior Penetration Tester (AI-Enabled Vulnerability Research) | London Hybrid | £600 per day PAYE + 12.07% Holiday Pay

We're supporting a leading global financial services organisation seeking an experienced Senior Penetration Tester to join a high-profile cyber security initiative focused on AI-enabled vulnerability discovery, offensive security testing and application security assessment. This role combines traditional penetration testing expertise with the use of frontier AI models and advanced security tooling to identify genuine exploitable vulnerabilities across critical applications and Internet-facing platforms. The successful candidate will play a key role in validating security findings, reducing false positives and improving remediation outcomes.

Contract Details:

• £600 per day PAYE + 12.07% Holiday Pay
• London Hybrid (2-3 days per week)
• ASAP Start c. 1st week of August
• Initial 6 month contract with potential extension

Key Experience Required:

• Strong Penetration Testing and Offensive Security experience
• Vulnerability Research and Security Assessment experience
• Web Application and API Security Testing
• Source Code Review and Secure Code Analysis
• Experience validating genuine exploitability and attack paths
• Knowledge of AI/LLM technologies and AI-assisted security testing
• Experience using AI tooling to support vulnerability discovery or code analysis
• Cloud Security knowledge (Azure, AWS or GCP)
• Strong stakeholder engagement and communication skills
• Ability to produce clear technical reports and remediation recommendations

Desirable Experience:

• Red Teaming experience
• Bug Bounty or Security Research background
• Product Security or Application Security experience
• Experience developing AI-native security tooling, testing harnesses or guardrails
• Financial Services experience
• Relevant certifications such as OSCP, Crest, GPEN or similar

Responsibilities:

• Conduct penetration testing and offensive security assessments across critical applications and platforms
• Use AI-enabled tooling and frontier models to accelerate vulnerability identification and validation
• Perform manual testing to confirm exploitability and assess business risk
• Review source code and security findings to identify genuine vulnerabilities
• Support reduction of vulnerability backlogs through effective triage and validation
• Work closely with engineering and security teams to drive remediation activities
• Develop repeatable testing methodologies, standards and guardrails
• Produce high-quality technical reports and security recommendations
• Contribute to the evolution of AI-assisted security testing capabilities

Ideal candidates will have proven penetration testing or vulnerability research experience alongside exposure to AI-assisted security testing, code analysis or AI-driven vulnerability discovery within large enterprise environments.

Robert Half Ltd acts as an employment business for temporary positions and an employment agency for permanent positions. Robert Half is committed to diversity, equity and inclusion. Suitable candidates with equivalent qualifications and more or less experience can apply. Rates of pay and salary ranges are dependent upon your experience, qualifications and training. If you wish to apply, please read our Privacy Notice describing how we may process, disclose and store your personal data: