Staff Attack Engineer, AI/LLM

Get to Know Us
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.

Summary
We are hiring a Staff Attack Engineer specializing in AI/LLM security to join our team. You will break AI and agentic systems and turn that research into automated attacks inside NodeZero, our autonomous pentesting platform.

This is not consulting or manual pentesting; the goal is to build repeatable, scalable attack patterns that run autonomously across customer environments. You’ll also help drive our LLM-powered offensive capabilities and act as a technical leader for AI/LLM offense.

Essential Functions
Attacking AI/LLM Systems

• Break AI and agentic systems and translate that research into automated, repeatable attack modules for NodeZero.
• Design and execute prompt injection and defense evasion attacks, focusing on generalized, reusable patterns.
• Conduct tool-use exploitation, abusing LLM agents’ access to code, file systems, APIs, and databases for attacker-realistic outcomes (e.g., context poisoning, RCE, data exfiltration, privilege escalation).
• Target AI infrastructure (model serving, training pipelines, vector databases, GPU/MLOps tooling) with an understanding of real-world enterprise deployments and misconfigurations.
• Research and apply model and supply chain attacks (poisoning, training data extraction, adversarial inputs, deployment pipeline abuse).
• Perform threat modeling for agentic systems, mapping trust boundaries and attack surfaces and turning them into concrete attack paths.
• Apply a strong productization mindset, turning manual techniques into safe, reliable, and scalable automated tooling.

Building with LLMs

• Build and extend LLM-powered applications (prompting, structured output, agentic workflows).
• Design with production concerns in mind: cost, safety and hallucination guardrails, reliability, and observability.
• Design and extend microservices that orchestrate LLM tasks and integrate with NodeZero and related offensive workflows.

Competencies / Requirements

• Expert-level Python and software engineering skills.
• Solid penetration testing fundamentals and understanding of common attack chains.
• Familiarity with AI/LLM security frameworks (e.g., OWASP Top 10 for LLMs, MITRE ATLAS).
• Experience in a security product or offensive security team, ideally with shipped offensive capabilities or tooling.
• Proven ability to break AI/LLM and agentic systems.
• Clear understanding of trust boundaries around AI tools, data sources, and permissions, and how to systematically test and exploit them.
• Expert-level ownership – drives high-complexity, high-risk programs and sets strategy, not just execution.
• Self-motivated – identifies problems and builds solutions proactively.
• Industry obsessed – tracks the fast-moving AI security landscape and can speak to recent developments, new attacks, and where the field is heading.

Nice-to-Have

• Experience with other cloud AI services (e.g., Azure OpenAI, GCP Vertex AI).
• Contributions to AI security research (blog posts, conference talks, CVEs, open-source tools).
• Experience with AWS Bedrock and AWS Agent Core.
• Familiarity with graph databases (e.g., Neo4j).
• Background in traditional exploit development or vulnerability research.
• CTF experience, particularly in AI/ML-focused challenge categories.

Perks of Horizon3

• Inclusive Team: We value diversity and promote an inclusive culture where everyone can thrive.
• Growth Opportunities: Be part of a dynamic and growing team with numerous career development opportunities.
• Innovative Culture: Work in a collaborative environment that encourages creativity and out-of-the-box thinking.
• Remote Work: We are a 100% remote company. Enjoy the convenience and work-life balance that comes with remote work.
• Competitive Compensation: We offer competitive salary, equity and benefits. Our benefits include health, vision & dental insurance for you and your family, a flexible vacation policy, and generous parental leave.

Compensation And Values
At Horizon3, we believe that our people are our greatest asset, and our compensation philosophy reflects this core value. We are committed to fostering an environment where all employees feel valued, respected, and rewarded for their contributions. Our compensation structure is designed to be fair, competitive, and transparent, ensuring that every team member is recognized and compensated equitably across roles, levels, and locations.

In accordance with various State’s transparency regulations, we provide the following salary range information for this position:

• Base salary range: $223,000 - $275,000 annually. The exact salary will be determined based on the selected candidate’s location, qualifications, experience, and relevant skills.
• Additional compensation: All full-time roles are eligible for an equity package in the form of stock options.

You Belong Here
Horizon3 is not just an equal opportunity employer - we are a community that values diversity, equity, and inclusion as fundamental principles of our culture and success. We are dedicated to fostering a workplace where everyone feels welcome and respected, regardless of race, color, religion, sex, national origin, age, disability, veteran status, sexual orientation, gender identity or expression, genetic information, marital status, or any other legally protected status by law.

Our commitment to diversity and inclusion means we strive to attract, develop, and retain a workforce that reflects the varied communities we serve. We believe that diverse perspectives drive innovation and strengthen our ability to create cutting-edge cybersecurity solutions. At Horizon3, every team member is valued and supported in an environment that encourages personal and professional growth.

We welcome candidates from all backgrounds and experiences, and we encourage all qualified individuals to apply. Come be a part of Horizon3, where your unique contributions are recognized, and your potential is limitless.

Other Duties
Please note this job description is not designed to cover or contain a comprehensive listing of activities, duties or responsibilities that are required of the employee. Duties, responsibilities, and activities may change at any time with or without notice.