Head of Proactive Security

About Nebius: Nebius is leading a new era in cloud infrastructure for the global AI economy. We are building a full-stack AI cloud platform that supports developers and enterprises from data and model training through to production deployment, without the cost and complexity of building large in-house AI/ML infrastructure. Built by engineers, for engineers. From large-scale GPU orchestration to inference optimization, we own the hard problems across compute, storage, networking and applied AI. Listed on Nasdaq (NBIS) and headquartered in Amsterdam, we have a global footprint with R&D hubs across Europe, the UK, North America and Israel. Our team of 1,500+ includes hundreds of engineers with deep expertise across hardware, software and AI R&D. The role Nebius is looking for a Head of Proactive Security to   establish   and lead the Proactive Security pillar. Reporting directly to the CISO, this leader will manage the Red Team, Penetration Testing, Threat Hunting, and Threat Intelligence teams.     The role   is responsible for   anticipating   relevant threats, challenging Nebius's defenses,   identifying   exploitable weaknesses, hunting for adversary activity that may evade existing controls, and converting findings into measurable security improvements.     This is a hands-on leadership position for someone who combines offensive-security depth, threat-led thinking, strong operational judgment, and the ability to influence product, engineering, infrastructure, and security stakeholders.       Your responsibilities will include:   Pillar strategy and leadership     Define the Proactive Security strategy, operating model, roadmap, priorities, budget, and success measures in alignment with   Nebius's   business   objectives   and threat profile.     Build, lead, and develop high-performing Red Team, Penetration Testing, Threat Hunting, and Threat Intelligence teams.     Create a unified intelligence-led program in which threat intelligence informs testing and hunting, and findings continuously improve defensive controls.     Prioritize work based on crown jewels, material attack paths, emerging threats, major technology changes, incidents, and business risk.     Establish clear team charters, engagement models, escalation paths, quality standards, and career-development frameworks.     Provide the CISO and senior leadership with clear visibility into adversary exposure, validated weaknesses, emerging threats, and remediation progress.     Red Team and adversary emulation     Lead realistic, intelligence-led adversary simulations across cloud, identity, applications, infrastructure, endpoints, networks, and operational processes.     Design campaigns that evaluate prevention, detection, response, escalation, and recovery capabilities against relevant threat scenarios.     Develop and   maintain   adversary-emulation plans mapped to relevant threat actors, tactics, techniques, and procedures.     Ensure every engagement   operates   under documented authorization, rules of engagement, safety controls, deconfliction procedures, and evidence-handling requirements.     Deliver concise technical and executive reporting that explains   demonstrated   impact, attack paths, root causes, and prioritized improvements.     Penetration testing and continuous security validation     Own the risk-based penetration-testing program for   Nebius   products, applications, APIs, cloud environments, infrastructure, and critical internal systems.     Define testing standards, scoping criteria, methodologies, quality assurance, retesting, and reporting requirements.     Coordinate internal testing and specialized external providers while   maintaining   consistent quality and risk prioritization.     Partner with Product, Engineering, Infrastructure, and Security teams to integrate testing into major launches, architectural changes, and high-risk initiatives.     Track findings through validation, remediation, exception, and closure, and   identify   systemic or recurring weakness patterns.     Expand automation and continuous validation where it improves coverage without replacing expert-led testing and judgment.     Threat hunting     Establish a hypothesis-driven threat-hunting program across endpoint, identity, cloud, network, workload, application, and SaaS telemetry.     Prioritize hunts using threat intelligence, incidents, environmental changes, control gaps, and emerging adversary techniques.     Search for active, historical, or previously undetected malicious behavior that may not trigger existing alerts.     Turn validated hunt findings into new detections, telemetry requirements, response playbooks, hardening actions, and future hunt hypotheses