Senior/Staff Attack Engineer, Rapid Response

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 to join the team behind our Rapid Response product. You will research and productize real-world exploitation techniques so customers can quickly understand whether newly disclosed or actively exploited vulnerabilities affect their environments—and what an attacker could do next.

You will focus on high-consequence vulnerabilities that are actively exploited, newly disclosed, or likely to generate significant attention - from CISA Known Exploited Vulnerabilities (KEVs) and Zero-Days to N-Days and emerging attack techniques. You will turn vulnerability research and attacker tradecraft into safe, repeatable, automated attack capabilities for the issues that are in the news, creating urgent customer concern, or most likely to affect the broader security community. This is not a traditional consulting or manual-pentesting role. Your work will help

security teams rapidly validate exposure, prioritize remediation, and verify that defenses are working.

What You’ll Do

• Research and reproduce high-consequence vulnerabilities across enterprise networks, applications, identity systems, cloud environments, and infrastructure—including CISA KEVs, CVEs, N-Days, and Zero-Days.

• Study attacker tactics, techniques, procedures, and campaigns observed in the wild, including tradecraft not tied to a single CVE.

• Turn vulnerability research and real-world attacker behavior into safe, repeatable proof-of-exploit capabilities, attack paths, and automated modules for Rapid Response and NodeZero.

• Demonstrate realistic impact—including privilege escalation, credential access, lateral movement, persistence, and data access—without unnecessary disruption.

• Validate remediation and containment by safely retesting vulnerabilities and security controls.

• Improve execution speed, reliability, observability, and evidence quality while collaborating with research, product, and engineering teams.

What You Bring

• Strong Python and software engineering skills, including experience building, testing, and operating production-quality tooling.

• Solid penetration testing, vulnerability research, and exploit-development fundamentals.

• Hands-on experience with enterprise networks, applications, identity systems, cloud environments, or endpoint security.

• Demonstrated ability to reproduce vulnerabilities and convert manual techniques into reliable automation.

• Understanding of common attack chains, trust boundaries, authentication and authorization, privilege escalation, and lateral movement.

• Ability to balance speed, safety, reliability, coverage, and actionable evidence.

• Curiosity about how attackers exploit newly disclosed vulnerabilities and how defenders can validate exposure quickly.

• Strong ownership, judgment, and communication skills in ambiguous or time-sensitive situations.

Nice to Have

• Experience with CISA KEVs, CVE analysis, N-Day research, Zero-Day research, or responsible disclosure.

• Background in incident response, threat hunting, purple teaming, or security operations.

• Experience with AWS, Azure, GCP, Kubernetes, Active Directory, Entra ID, Okta, or hybrid environments.

• Experience with exploit development, reverse engineering, malware analysis, or vulnerability research.

• Contributions to security research, CVEs, conference talks, open-source tools, or technical publications.

• CTF experience or equivalent hands-on offensive security practice.

• Bachelor’s Degree in Computer Science, Computer Engineering or related field.

• OSCP (Offensive Security Certified Professional) or equivalent certifications.

Travel Required

We are a fully remote company, and this job may require up to 10% of travel to be successful.

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.

• 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.

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: $230,000 - $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.

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.