Principal Software Engineer

** Overview*
* Secure the next generation of Copilot experiences

The Copilot Security Engineering team sits at the core of Microsoft's mission to deliver secure, trusted, and human-centered AI experiences across Microsoft's Copilot offerings. We build the systems that detect, evaluate, and defend against emerging AI threats, including prompt injection, memory poisoning, data exfiltration, adversarial inputs, and abuse of agentic workflows. Our goal is to establish industry-leading security protections that enable customers to confidently adopt AI at scale.

Our team combines security engineering, AI systems expertise, and threat research to identify emerging risks, develop novel defenses, and continuously measure their effectiveness in production. We work closely with product teams, Microsoft Research, and platform organizations to ensure security is built into every layer of the Copilot ecosystem.

We are looking for a Principal Software Engineer to set technical direction and own the architecture of AI threat detection and defense capabilities spanning multiple Copilot experiences. You will turn ambiguous, evolving threats into an actionable engineering strategy and reusable platform protections, aligning partners on priorities, interfaces, and measurable security outcomes.

This is a hands-on individual contributor role at the intersection of security, AI, and large-scale distributed systems. You will design and write production code, lead complex work from threat discovery through deployment and operation, and remain accountable for the effectiveness and reliability of the defenses you deliver. Your impact will extend through cross-team architectural decisions, partner influence, and mentorship, rather than people management.

This position is based in Redmond, Washington and requires the employee be in the office a minimum of 3 days per week.

Microsoft's mission is to empower every person and every organization on the planet to achieve more. As employees we come together with a growth mindset, innovate to empower others, and collaborate to realize our shared goals. Each day we build on our values of respect, integrity, and accountability to create a culture of inclusion where everyone can thrive at work and beyond.

** Responsibilities*
* + Define and drive a multi-team technical strategy for Copilot security. Translate emerging threats and product needs into prioritized engineering investments, architectural decisions, and an executable roadmap with clear ownership and success measures.

+ Own the end-to-end architecture and hands-on implementation of detection and defense systems for prompt injection, indirect prompt attacks, memory poisoning, data exfiltration, model misuse, and abuse of agentic workflows. Resolve ambiguous problems across AI workflows, tools, orchestration layers, trust boundaries, and platform integrations.

+ Build reusable security services, classifiers, evaluation frameworks, telemetry pipelines, and risk assessment capabilities. Establish extensible interfaces and integration patterns that enable multiple Copilot teams to adopt durable protections instead of duplicating point solutions.

+ Define security effectiveness measures and release criteria with partners, including attack coverage, detection quality, false-positive impact, and mitigation effectiveness. Use adversarial evaluations and production telemetry to validate improvements, detect regressions, and balance protection with latency, reliability, cost, and customer experience.

+ Lead threat modeling and architectural security reviews across team boundaries. Partner with security researchers, Microsoft Research, product teams, and platform organizations to investigate emerging attack techniques, validate…