Senior Attack Engineer, External

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 assessmen...

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” sec...

We're looking for a Senior Attack Engineer to drive key workstreams within our external attack capabilities in NodeZero, our autonomous pentesting platform.

Design, build, and maintain highly scalable reconnaissance workflows that discover, enumerate, and fingerprint external-facing assets and services in production-grade Python.
Research, explore, and parse large volumes of external-facing data, including unstructured and inconsistent sources, and turn it into accurate, actionable information.
Develop robust approaches to data that is hard to reason about in code, such as free-form banners, web content, documents, and error output, and build parsing and enrichment that holds up across the long tail of real environments.
Collect, store, and connect high volumes of information, and extend our attack-path modeling and graph data model to represent new identity, privilege, and relationship paths.
Traverse identity relationships across the external surface, such as accounts, tenants, SSO and federation, exposed credentials, and third-party services, to find paths from exposure to compromise.
Automate multi-step attack workflows that chain discovery, credential access, initial access, and post-exploitation into complete, safely proven attack paths.
Research emerging external tradecraft and turn it into production attack content, with an emphasis on techniques that still succeed against hardened, well-monitored targets.
Stand up and maintain representative test environments to validate, demonstrate, and regression-test attack scenarios.
Build for production safety and scale: respect target and customer environments, rate limits, and scope while running across very large attack surfaces.
Contribute to priorities and the coverage roadmap based on real customer environments, threat intelligence, and emerging techniques.
Mentor teammates and proactively support their growth, and help define team standards for code quality, research rigor, and operational safety.
Collaborate cross-functionally with engineers, product managers, and customer-facing teams, and author internal documentation and external research and blog posts.

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.
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.

Deep, hands-on offensive experience against external attack surfaces, from reconnaissance through initial access and post-exploitation.
5+ years of hands-on experience in offensive security, security research, and/or security-focused software engineering, with recent work building and shipping offensive tooling.
Demonstrated experience building reconnaissance and discovery systems that run at scale, not just one-off scripts.
Strong skill at researching and parsing large amounts of messy, unstructured external data and turning it into usable, trustworthy information.
Experience collecting, storing, and connecting high volumes of data, and reasoning about it as relationships, such as identities, assets, and trust.
Command of identity-focused tradecraft: credential access, password and token attacks, SSO and federation weaknesses, and moving among identities, tenants, and services.
Experience automating multi-step attack workflows end to end.
Strong software engineering fundamentals with Python, and a track record of shipping and maintaining production-quality code, not just scripts and proofs of concept.
Ability to independently research unfamiliar systems and technologies and rapidly build deep, practical expertise.
Strong written and verbal communication, including clear technical documentation.
A passion for building products, not just finding vulnerabilities.
OSCP (or OSEP, CRTO, or equivalent offensive certifications).
Experience with large-scale internet data sources and tooling, such as certificate transparency, passive DNS, and internet-wide scanning.
Experience with cloud, SaaS, and hybrid identity attack surfaces (Entra ID, Okta, AWS, and similar), including on-prem to cloud pivots.
Experience with external to internal pivoting and how perimeter footholds lead into additional access.
Experience with graph databases and attack-path analysis, and with data lake or high-volume data storage and processing.
Experience developing or contributing to offensive or recon tooling
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.