Horizon3 uses real-world attacks to safely show what attackers can actually do in your environment—so you can fix and prove what matters. Backed by NEA.
About the role
We're looking for an AI Researcher to build the agents that turn our offensive knowledge into defensive action. You'll build agents that reason from a proven attack path to the specific control changes that break it - EDR policy, firewall and segmentation rules, conditional access, detection content, cloud IAM, GPO - apply or stage those changes in the customer's environment, and then prove the fix by re-running the attack.
What they're looking for
- Strong ML engineering experience building, evaluating, and deploying production AI systems, with hands-on work in deep learning, transformer models, and PyTorch
- Hands-on experience with at least one of: post-training large language models (supervised fine-tuning, distillation, preference optimization, RL), or designing agentic systems with tool use, planning, and long-horizon execution that hold up outside a demo
- A track record of building evaluation systems for open-ended tasks where there is no clean label and success is judged by outcome
- Experience reasoning over structured, heterogeneous, messy real-world data — configurations, graphs, logs, policy documents — rather than clean benchmark datasets
- Strong software engineering fundamentals and a track record of shipping and maintaining production-quality code in Python, not just scripts and proofs of concept
- Experience with data pipelines, distributed systems, and cloud infrastructure, preferably AWS
More about this role
Horizon3 is a fast-growing, remote cybersecurity company dedicated to the mission of enabling organizations to proactively find and fix and verify exploitable attack vectors before criminals exploit them. Our flagship product, the NodeZeroTM platform, delivers production-safe autonomous pentests and other key assessment operations that scale across the largest internal, external, cloud, and hybrid cloud environments. NodeZero has been adopted by organizations of all sizes, from small educational institutions to government agencies and Global 100 enterprises. It is used by ITOps/SecOps teams, consulting pentesters, and MSSPs and MSPs.
We are a fusion of former U.S. Special Operations cyber operators, startup engineers, and formerly frustrated cybersecurity practitioners. We're committed to helping solve our common security problems: ineffective security tools, false positives resulting in alert fatigue, blind spots, "checkbox” security culture, cybersecurity skills shortage, and the long lead time and expense of hiring outside consultants. Collectively, we are a team of learn it alls, committed to a culture of respect, collaboration, ownership, and results.
We're looking for an AI...
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