Senior GenAI Security Engineer

About Lenstra

Lenstra was founded by engineers with a passion for Computer Science and a track record of delivering high-quality solutions. We work at the intersection of Cloud, DevOps, Data Platforms, AI and IT Security, helping top-tier clients in Banking, Insurance, Luxury and Tech solve their hardest technical challenges. Our approach is holistic: we build solutions that are as elegant as they are impactful.

The mission

You’ll join the Application Security team of one of our clients, working directly with its Director of AppSec. One goal: every AI project in the company ships secure, from design to production.

About the role

🛡️ You will be the go-to expert on AI and cloud application security, setting the policies and best practices teams follow company-wide.

🤖 You will build and run the controls that secure AI and agentic systems: sandboxes, guardrails, compliance checks, vulnerability management.

🔍 You will lead design reviews, threat modeling and architecture assessments before risks reach production.

🔑 You will deploy agent identity, authentication and access control (RBAC/ABAC) with the Core & Architecture team, on-prem and in the cloud.

☁️ You will help dev teams fix cloud and IaC findings, plug security tooling into CI/CD with low noise and zero slowdown, and track security KPIs.

What we look for

Mindset

Builder, not auditor. You ship working tools, not just findings reports.

Translator. You can explain a code vulnerability to a developer and a business risk to a director, in French and English.

Ahead of the curve. You follow AI security research and adversarial TTPs, and bring them back to the job.

Must-haves

5+ years of hands-on AppSec on modern architectures: cloud, containers, serverless, APIs

Deep cloud security expertise on AWS

Solid grasp of LLM architecture, embeddings, vector databases, RAG and inference

Hands-on experience securing MCP servers, skills and agentic coding tools (e.g. Claude Code)

Experience on OWASP Top 10 for LLMs and for Agentic Applications

Experience on SAML, OAuth2, OpenID Connect

Docker, Kubernetes (EKS/ECS) security and image vulnerability scanning

IaC and automation: Terraform, Ansible, CloudFormation

Linux and networking (TCP/IP, UDP, HTTP/S, SSH)

Strong coding skills in python

Fluent French and English

Nice-to-haves

- Threat modelling or security audit experience

- MLOps pipelines and cloud AI services (SageMaker, Bedrock, Vertex AI, Azure ML)

What we offer

- TJM between 700 and 800, based on seniority and interview performance. No surprises.

- Remote policy: 2 days of home office per week

- A role at the frontier of a field most security teams are still figuring out.