--- title: 'Senior Attack Engineer, Internal Systems at Horizon3 AI' canonical: 'https://feeny.ai/job/senior-attack-engineer-internal-systems-horizon3-ai-united-states-fejaky94p1d0' type: 'job' last_seen: '2026-11-07' --- # Senior Attack Engineer, Internal Systems at Horizon3 AI - **Company:** [Horizon3 AI](https://feeny.ai/companies/horizon3-ai) - **Location:** United States - **Employment:** full-time - **Work type:** remote - **Posted:** 2026-10-26 - **Last confirmed live:** 2026-11-07 - **Apply:** https://jobs.ashbyhq.com/horizon3ai/4c61e8cd-28db-407f-b540-37298d3e0ac9 ## Job description Get to Know Us Horizon3.ai 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're seeking a Senior Attack Engineer who blends deep software engineering expertise with a passion for cybersecurity. In this role, you’ll independently lead complex internal network and Active Directory attack projects in NodeZero, our autonomous pentesting platform. Internal enterprise networks and Active Directory remain key targets in modern breaches, and it is exactly where our customers most need NodeZero to find and safely prove exploitable attack paths. The environments we operate in are hardening fast, while tradecraft continues to evolve across network protocols, identity systems, management planes, and hybrid environments. We need someone who can research and weaponize real-world vulnerabilities and misconfigurations into reliable product capabilities. You'll design and build production-grade systems that drive the offensive capabilities of the NodeZero platform. You'll own complex attack capabilities from research and technical design through production delivery and ongoing operation, making consequential technical decisions within the internal network scope. You'll also strengthen the team through proactive mentorship, thoughtful code reviews, and improvements to our engineering and research practices. This is not consulting or manual pentesting. The goal is to turn cutting-edge, often manual techniques into safe, reliable, repeatable autonomous attacks that scale across the largest internal environments in the world. If you love both breaking internal network infrastructure and building scalable software to automate it, this is the seat. ## What You’ll Do - Research and develop novel attack capabilities for integration into the NodeZero platform, focusing on autonomous red teaming, internal network breach techniques, and offensive security automation. - Research emerging internal tradecraft (network protocol exploitation, Active Directory abuse, management-plane attacks, delegation, credential access, and hybrid identity pivots) and turn it into production attack content. - Design, build, and maintain production-grade Python systems, making clear tradeoffs between attack effectiveness, operational safety, reliability, scalability, and maintainability. - Acquire, configure, and exploit modern, hardened internal test environments to validate and demonstrate complex attack scenarios. - Monitor public vulnerability databases and threat intelligence sources to stay current on emerging threats and incorporate them into internal network attack modules. - Extend and maintain platform architecture and graph data models for new identity, privilege-escalation, and lateral-movement paths. - Help shape the team's coverage priorities using customer needs, threat intelligence, and emerging techniques; scope deliverable projects and proactively raise risks and tradeoffs. - Mentor teammates and improve team processes, code quality, architectural standards, and research safety practices. - Partner cross-functionally with engineers, product managers, and customer-facing teams to resolve issues, enhance features, author technical documentation, and drive customer value. ## What You’ll Bring - Deep, hands-on offensive security experience against internal enterprise networks and Active Directory, from initial foothold through domain and enterprise compromise. - Expert-level proficiency in Python for large-scale development and a track record of shipping and maintaining tested, documented, production-quality code. - Strong command of internal network attack techniques, including network protocol exploitation, privilege escalation, lateral movement, and credential access. - Experience with object-oriented design, API integration, data structures, and building scalable system components in fast-paced product environments. - Experience designing complex software components or systems, accounting for extensibility, operational safety, performance, and long-term maintenance, and explaining the reasoning behind architectural decisions. - A track record of independently leading complex, high-impact technical projects with significant risk, making sound decisions under ambiguity, and identifying business implications and delivery risks before they become critical issues. - Strong written and verbal communication, including clear technical documentation and the ability to explain design choices, risks, and tradeoffs to engineers and non-technical stakeholders. - Demonstrated investment in teammates' growth through proactive mentorship, architectural feedback, and code reviews, along with experience improving team processes, tooling, or technical standards. - Offensive security and software engineering background with a strong passion for turning security research into safe, maintainable product capabilities. What Sets You Apart - OSCP (or OSEP, CRTO, or equivalent offensive certifications). - Experience researching and implementing attacks against SCCM, Windows Admin Center, and other modern Windows management-plane attack surfaces. - Familiarity with containerization (Docker, Kubernetes) and working with relational (Postgres) and graph (Neo4j) databases. - Experience developing or contributing to offensive tooling like BloodHound, Impacket, netexec, etc. - Hands-on experience with graph databases (Neo4j) and attack-path analysis, including extending models to represent new identity and privilege relationships. - Experience integrating security research into production, multi-tenant SaaS, with attention to testing, reliability, and customer safety. - Public contributions to the field: open-source tools, technical blog posts, conference talks, or published CVEs. - Experience building production-safe autonomous or automated offensive tooling, including applying AI/LLM technologies to enhance attack workflows. Travel Required We are a fully remote company, and this job may require up to 10% of travel to be successful. ## 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: $206,278 - $242,680. 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. Perks of [Horizon3](http://Horizon3.ai) - 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. - 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. - 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. 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, 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. 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. Application Note In any materials you submit, you may redact or remove age-identifying information such as age, date of birth, or dates of school attendance or graduation. You will not be penalized for redacting or removing this information. ## About Horizon3 AI ## Company Overview - **One-liner**: Horizon3.ai provides an autonomous penetration testing platform (NodeZero) that safely hacks production environments to identify and fix exploitable attack paths using AI. - **Entity Type**: Private (Series D – latest funding round in 2026, led by Prosperity7 Ventures) - **Headquarters**: San Francisco, California, United States (447 Battery Street, San Francisco, CA 94111) - **Founded**: 2019 - **Founders**: Snehal Antani (Co-Founder & CEO); founded by a mix of US Special Operations, US National Security, and cybersecurity industry veterans ## Core Business - **Primary industry**: Cybersecurity (autonomous penetration testing, vulnerability management, continuous security validation) - **Target customers**: B2B – large enterprises, Fortune 100, government agencies (NSA, CISA), healthcare providers, financial services, manufacturing, education, public sector - **Mission**: “Turn the map around” – using the attacker’s perspective to help enterprises prioritize defensive efforts. The company aims to shift the advantage from attackers to defenders by fighting AI with AI. ## Products & Services - **[NodeZero®](https://horizon3.ai/)**: Autonomous penetration testing SaaS platform. Safely runs real attack techniques in production environments (no agents, no disruption). Discovers and chains exploitable vulnerabilities, misconfigurations, harvested credentials, and dangerous defaults across external, identity, on-prem, cloud, and Kubernetes attack surfaces. Also includes Active Directory password auditing and phishing impact testing. Continuously validates fixes and repeats autonomously. ## Market Standing - **Valuation**: Not publicly disclosed - **Key Metrics**: - Annual Revenue: **$35.5M** (per LinkedIn) - Total Funding: **$187M** (per LinkedIn) / **$181M** (per CB Insights – conflicting reports; both cited) - **225,000+** production-safe tests completed - **5,000+** customers - **Notable Investors/Partners**: - SignalFire (lead in Seed, Series A, Series B) - Craft Ventures (lead Series C) - Prosperity7 Ventures (lead Series D – 2026) - **Growth Signals**: - Ranked **#1 in Security** on the 2025 Inc. 5000 list - **#3 overall** on the 2025 Deloitte Technology Fast 500 - Fast Company’s **Most Innovative Companies** (2026) – #1 in Security - Named to the **Fortune Cyber 60** (2023 & 2025) - Two-time **Black Unicorn Award** winner - Headcount grew **115.5% YoY** to 341 employees (LinkedIn) - Active job postings up **168.2% YoY**; operates in 14 countries ## Competitive Advantages - **AI-driven autonomous testing** that learns from hundreds of thousands of tests and uses the right AI (ML, GenAI) for each problem – delivers evidence-based results with **zero hallucinations**. - **Production-safe** – zero downtime across all production tests, trusted by the world’s most sensitive high-security environments (NSA, CISA, Fortune 10, major healthcare). - **No agents required** – fully self-service SaaS, safe to run continuously. - **Real attack techniques** – not a scanner; shows actual attacker paths and impact. - **Rapid verification** – instantly confirms fixes and repeats the cycle, enabling a continuous validation loop. ## Strategic Focus - **Continuous validation** – driving a loop of test-fix-verify-repeat autonomously. - **Fighting AI with AI** – building NodeZero to operate at machine speed against AI-powered attacks. - **Global expansion** – already in 14 countries, with active hiring in EMEA, APAC, and the Americas. - **Scaling the team** – 59 active job postings (as of mid-2026), with emphasis on engineering, sales, and customer success roles. ## Why Work Here - **Culture**: Rated **5.0/5.0 on LinkedIn** (76 reviews) with perfect scores for Culture (5.0), Career (4.9), Compensation (4.7), and Work-Life (4.6). Described as a “kick-ass organization hell bent on disrupting an industry” with a team of “motivated learn-it-alls.” - **Work Policy**: Remote-friendly (most roles listed as remote, HQ in San Francisco, CA). Offers flexibility across time zones. - **Notable Perks** (from Built In and LinkedIn): - Comprehensive healthcare (medical, dental, vision, FSA) - Life insurance, disability insurance - 401(k) with company matching - Equity and employee stock purchase plan - Generous parental leave and family medical leave - Performance bonuses - Job training, conferences, and customized development tracks - Promotion policies and career growth support - **Engineering Culture**: Built by US Special Operations and National Security veterans. Emphasis on high autonomy, real-world impact, and cutting-edge AI/security work. “If you want to be part of a kick-ass organization hell bent on disrupting an industry and keeping attackers at bay, let’s talk.” ## Sources 1. [horizon3.ai – Homepage](https://horizon3.ai/) 2. [horizon3.ai – About/Team](https://horizon3.ai/about-us/) 3. [LinkedIn – Horizon3.ai Company Page](https://www.linkedin.com/company/horizon3ai) 4. [Built In – Horizon3.ai Careers & Perks](https://builtin.com/company/horizon3ai) 5. [CB Insights – Horizon3.ai Profile](https://www.cbinsights.com/company/horizon-3-ai) ## Other roles at Horizon3 AI - [Director of Engineering, Threat Research](https://feeny.ai/job/director-of-engineering-threat-research-horizon3-ai-united-states-0fsq2qg04cee) — United States - [Senior Attack Engineer, GCP](https://feeny.ai/job/senior-attack-engineer-gcp-horizon3-ai-united-states-p7dypj66skxv) — United States - [Senior Attack Engineer, Kubernetes](https://feeny.ai/job/senior-attack-engineer-kubernetes-horizon3-ai-united-states-8bbsrmqpg924) — United States - [Senior Attack Engineer, OCI](https://feeny.ai/job/senior-attack-engineer-oci-horizon3-ai-united-states-06y0k0t6a5p9) — United States - [Staff Backend Engineer, Internal](https://feeny.ai/job/staff-backend-engineer-internal-horizon3-ai-united-states-eccvzb53mpb7) — United States - [Senior Sales Engineer (SLED)](https://feeny.ai/job/senior-sales-engineer-sled-horizon3-ai-united-states-agqan5xzy6d6) — United States - [Research Staff, Adversarial Intelligence](https://feeny.ai/job/research-staff-adversarial-intelligence-horizon3-ai-united-states-xxx9ghesv6ha) — United States - [Engineering Manager, Internal Attack](https://feeny.ai/job/engineering-manager-internal-attack-horizon3-ai-united-states-tx9j8q1pkfsx) — United States - [Senior Account Executive, SLED - New York](https://feeny.ai/job/senior-account-executive-sled-new-york-horizon3-ai-new-york-2d49m7hyp482) — New York, NY - [Senior Account Executive, SLED - Texas](https://feeny.ai/job/senior-account-executive-sled-texas-horizon3-ai-united-states-nkhqvten2p1s) — United States