Senior AI Security Researcher

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.

You'll lead offensive security research against AI agents and the infrastructure around them, and work with our engineers to turn your findings into detections, evaluations and defences in the product.

• Red-team AI agents across browser, code, enterprise and multi-agent environments.

• Research prompt injection, tool abuse, memory poisoning, identity and data-exfiltration attack chains.

• Build automated attack tooling and reusable evaluation suites that run in CI and for customers.

• Turn findings into detection rules, classifiers and policy controls with our engineers.

• Lead customer assessments and write findings that security leaders can act on.

• You've set a research agenda and delivered findings that changed the product.

• A growing regression suite captures the attack techniques you've found.

• Customers have received assessments with clear, reproducible evidence.

• 6+ years in offensive security, application security, red teaming or vulnerability research.

• A record of original findings, such as CVEs, bug bounties, published research or conference talks.

• Hands-on experience attacking LLM applications or agents, including tool calling, retrieval, memory and permissions.

• Strong Python and a systems language, with a habit of building your own tooling.

• Clear communication of rigorous findings to engineers and executives.

• Working knowledge of MITRE ATLAS or the OWASP Top 10 for LLM applications.

• Montenegrin, Serbian, Bosnian or Croatian.

Radical transparency. We believe the best work happens when everyone feels able to give and receive honest, constructive feedback.

Public service. We see AI security as a form of public service. Getting the AI transition right means putting the right infrastructure in place to manage the threats that come with it, and our work helps protect the institutions and services society depends on.

Fail fast. We test ideas early, seek feedback and learn quickly. We experiment rapidly and change course when something isn't working, without compromising on security.

Pragmatism, not dogmatism. We choose approaches based on how well they solve the problem. That means combining established cybersecurity methods with frontier AI research, questioning our assumptions, and changing our minds when the evidence changes.

• Salary: €40,000–€95,000 gross per year

• Competitive equity to share in Refractal's growth

• Pension contribution

• Private medical and dental cover

• Visa and relocation support