Principal 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, 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.

We are a fusion of former U.S. Special Operations cyber operators, startup engineers & operators, and formerly frustrated cybersecurity practitioners. We're 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. Collectively, we are a team of learn it alls, committed to a culture of respect, collaboration, ownership, and results.

An Overview

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 Horizon3.ai ↗. 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 operate at the intersection of company strategy and technical direction. 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.

What You’ll Do

Company-wide Technical Leadership & Scope

• 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; establish the outcomes and decision principles against which teams execute.

• Lead cross-company initiatives that require alignment across Attack Engineering, Platform, Product, customer-facing teams, and other technical functions.

• Diagnose systemic blockers in architecture, process, operating model, or technical capability and drive durable resolution.

• Define company-wide standards for reliability, safety, observability, evaluation, testing, cost management, and operational readiness in LLM-powered offensive systems.

• Develop P5 engineers and other senior technical leaders, multiplying the organization’s capacity to reason about and deliver AI/LLM security capabilities.

• Communicate clearly with executives, technical leaders, and external stakeholders; bring the organization through major technical transitions with clarity and composure.

Attacking AI/LLM Systems

• Own NodeZero's 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.

• Identify novel, high-leverage attack classes and establish the frameworks, abstractions, and coverage models needed to make them repeatable in NodeZero.

• 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.

• Ensure research becomes safe, reliable, scalable product capability rather than remaining isolated expertise or one-off demonstrations.

• Serve as the definitive internal technical authority on the hardest and most novel AI/LLM offensive problems; where appropriate, represent the company through technical writing, talks, research, or open-source contributions.

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.

What You’ll Bring

• 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.

• Demonstrated ability to define long-term technical vision, resolve the company’s hardest ambiguous problems, and drive execution through influence rather than direct authority.

• Company-wide technical judgment: able to make consequential tradeoffs across product value, safety, reliability, cost, speed, and maintainability.

• 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.

What Sets You Apart

• Experience setting technical direction or architecture across an engineering organization