About the role

As a Member of Technical Staff - Engineering (Security), you will own security across Collinear's infrastructure, products, and customer data. We build RL environments and training data for frontier AI labs and large enterprises. They trust us with sensitive data and access to their systems, and many of our environments run AI agents that are being trained to find and exploit vulnerabilities.

This is a senior, hands-on role. You will work alongside our researchers and engineering team to set the direction for, and implement, new security measures.

What you'll do

Harden the sandboxes where AI agents run untrusted code, including cyber tasks where agents are actively trying to break out

Own AWS security, including IAM design, least-privilege access, network boundaries, and short-lived credentials in place of long-lived keys

Build detection and response across our cloud and Kubernetes environments, and tune alerts so the team acts on them

Protect customer data from the moment it arrives to the moment we deliver, including access controls, secure delivery, and PII removal at terabyte scale

Lead customer security reviews and compliance work, from security questionnaires and supplier onboarding to SOC 2

Secure our software supply chain, including dependencies, CI/CD, secrets, and our GitHub organization

Set guardrails for engineers and coding agents that work directly against production infrastructure

Test our systems the way an attacker would, and fix what you find

About you

You have 8+ years of experience in security engineering, much of it securing cloud infrastructure in production

You have deep hands-on experience with AWS security, including IAM, CloudTrail, GuardDuty, KMS, and VPC design

You have an offensive security background, such as penetration testing, red teaming, or vulnerability research, and use it to decide what to defend first

You have isolated untrusted workloads with containers or microVMs, using tools such as gVisor, Firecracker, or Kata Containers, and know where that isolation tends to fail

You write production-quality code, ideally in Python, and prefer automation to manual process

You have built or grown a security program at a startup, and know how to prioritize when you can't fix everything at once

You explain risk clearly to engineers, leadership, and customers' security teams