Principal Attack Engineer, AI/LLM

Horizon3 is a fast-growing, remote cybersecurity company dedicated to the mission of enabling organizations to proactively find, 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 IT Ops/SecOps teams, consulting pentesters, and MSSPs and MSPs.
Special Operations cyber operators, startup engineers & operators, and formerly frustrated cybersecurity practitioners. Were committed to helping solve our common security problems: ineffective security tools and 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. We are hiring a Principal Attack Engineer specializing in AI/LLM security to define the long-term technical direction for AI/LLM offense at Horizon3. You will lead the company’s most complex and consequential efforts to break AI and agentic systems and turn that research into scalable, autonomous attack capabilities inside NodeZero, our autonomous pentesting platform. This is not consulting or manual pentesting; the goal is to establish durable, production-grade capabilities that materially expand how NodeZero finds and validates exploitable attack paths across customer environments. The focus is LLM-based applications: the chatbots, copilots, RAG pipelines, and AI agents that enterprises expose to employees, customers, and the internet.
You will shape the vision for AI/LLM offensive capabilities, partner with senior leadership on major technical and product decisions, and create the architecture, standards, and organizational alignment required for multiple teams to execute against that vision. This is a rare, company-wide role for a technical authority whose judgment influences the business and, where appropriate, the broader AI security field.
Define the long-term technical vision for AI/LLM offense and its role in NodeZero and the company’s broader product strategy.
Partner with senior engineering, product, and business leadership to shape priorities, investment decisions, risk posture, and the roadmap for AI/LLM offensive capabilities.
Set direction for the most complex, high-risk, and business-critical AI/LLM programs; Lead cross-company initiatives that require alignment across Attack Engineering, Platform, Product, customer-facing teams, and other technical functions.
Develop P5 engineers and other senior technical leaders, multiplying the organization’s capacity to reason about and deliver AI/LLM security capabilities.
Attacking AI/LLM Systems
Own NodeZeros coverage strategy for the OWASP Top 10 for LLM Applications (prompt injection, sensitive information disclosure, system prompt leakage, improper output handling, excessive agency, vector and embedding weaknesses, and data and model poisoning), and define where NodeZero should go beyond the list, particularly for multi-agent and tool-connected systems.
Set the company’s research and productization agenda for breaking AI and agentic systems, balancing technical opportunity, customer impact, safety, and strategic differentiation.
Direct the company’s approach to prompt injection, defense evasion, tool-use exploitation, context poisoning, remote code execution, data exfiltration, privilege escalation, and other agentic attack paths.
Set technical direction for assessing AI infrastructure, including model serving, training pipelines, vector databases, GPU/MLOps tooling, and enterprise deployment architectures.
Evaluate the strategic significance of model and supply-chain attacks such as poisoning, training-data extraction, adversarial inputs, and deployment-pipeline abuse, and determine how the company should respond.
Establish a durable threat-modeling approach for agentic systems that accounts for trust boundaries, identities, permissions, tools, data sources, downstream systems, and business impact.
Serve as the definitive internal technical authority on the hardest and most novel AI/LLM offensive problems; Building with LLMs
Set the long-term architecture for LLM-powered offensive applications, agentic workflows, evaluation systems, and their integration with NodeZero.
Establish company-wide principles for cost, safety, hallucination guardrails, reliability, observability, evaluation quality, and operational risk.
Guide the architecture of microservices and shared platforms that orchestrate LLM tasks across offensive workflows.
Lead architectural transformations when the existing approach cannot support the company’s scale, product ambitions, or safety requirements; document the vision, build the case, and bring engineers and leadership along.
Ensure the organization can operate and improve these systems over time through strong ownership, incident learning, measurable quality standards, and sustainable technical practices.
Exceptional Python and software engineering expertise, with deep experience designing systems that are secure, reliable, observable, and operable at scale.
Deep expertise in offensive security, penetration testing, exploit development, vulnerability research, or a closely related discipline.
Recognized expertise in AI/LLM and agentic-system security, including the ability to identify novel attack paths and translate them into durable technical strategy.
Deep command of the OWASP Top 10 for LLM Applications and MITRE ATLAS, combined with the judgment to extend beyond existing frameworks.
A track record of shipping or shaping high-impact security capabilities, platforms, research programs, or technical standards across multiple teams.
Proven ability to develop senior technical talent and multiply the mentorship capacity of an engineering organization.
Self-motivated, highly credible, and deeply engaged with the direction of the AI security industry.
Experience setting technical direction or architecture across an engineering organization or multiple product areas.
Industry-level contributions to AI security research through influential publications, conference talks, CVEs, open-source projects, or widely adopted techniques.
Experience shaping strategy for cloud AI platforms such as AWS Bedrock, AWS Agent Core, Azure OpenAI, or Google Vertex AI.
Deep experience with agentic architectures, tool-use security, retrieval systems, vector databases, graph databases such as Neo4j, or AI infrastructure security.
Background in traditional exploit development, vulnerability research, or building offensive security platforms at significant scale.
CTF experience, particularly in AI/ML-focused challenge categories.
Travel Required
We are a fully remote company, and this job may require up to
of travel to be successful.
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:
All full-time roles are eligible for an equity package in the form of stock options.
We value diversity and promote an inclusive culture where everyone can thrive.
Growth Opportunities:
Hybrid & Remote Work:
We embrace a mix of remote and hybrid work models depending on role and location, including our Chicago office, where some roles require regular in-office presence.
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.
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, hair length 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.
Application Note
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