Security Engineer (AI Red Team)

About this role

About Refractal Refractal is an AI security company building the infrastructure organisations need to defend against autonomous AI threats. 2026 has shown that generally capable intelligence is here. The challenge now is modernising security to stop AI-enabled threats, whether they come from internal agents going rogue or from attackers using AI to become more dangerous. Refractal was founded on cybersecurity and AI expertise from MIT, Microsoft, NASA and the U.S.

Navy. Our product lets organisations detect AI-enabled threats at low cost without sacrificing detection quality. We take a practical approach to AI risk, combining proven cybersecurity methods with frontier AI security research. Today, we work with governments and organisations that can't afford to get security wrong. We're backed by leading deep-tech and cybersecurity investors and are growing the team to deliver on this mission.

The role You'll test how deployed AI systems and agents fail under adversarial pressure. You'll run authorised, controlled security assessments, show what each finding means in practice, and work with our engineering and research teams to turn findings into stronger defences and repeatable tests. What you'll do Design and execute assessments of AI applications and agents, grounded in realistic attacker goals and clearly defined test scope.

Test realistic threats such as indirect prompt injection, misuse of connected tools, sensitive data exposure and attempts to cross permission boundaries. Build reproducible test cases and small testing tools that demonstrate security impact and distinguish reliable failures from one-off outputs. Analyse how model behaviour, application design, identity and permissions combine to create vulnerabilities. Document findings, recommend practical mitigations and retest fixes with the engineers responsible for the affected systems.

Success in your first six months You've established a repeatable assessment approach that connects realistic adversaries, test scenarios and security outcomes. You've produced actionable findings with reproducible evidence and helped validate the resulting fixes. You've built a growing set of regression tests that captures recurring failure modes and checks whether fixes hold. About you: essential Hands-on experience in offensive security, application security testing or adversarial testing of AI systems.