Senior Internal Red Team Engineer

About Horizon3.ai

Horizon3.ai is a fast-growing, remote cybersecurity company dedicated to enabling organizations to proactively find, fix, and verify exploitable attack vectors before criminals exploit them. Our flagship NodeZeroTM platform delivers production-safe autonomous pentests across internal, external, cloud, and hybrid cloud environments. We are a fusion of former U.S. Special Operations cyber operators, startup engineers, and cybersecurity practitioners committed to solving common security problems like ineffective tools, alert fatigue, and the cybersecurity skills shortage. We foster a culture of respect, collaboration, ownership, and results.

Role Summary

As a Senior Internal Red Team Engineer, you will be passionate about offensive cybersecurity, bringing extensive hands-on experience in cloud and web application penetration testing. Your primary mission involves emulating advanced, real-world adversaries to test Horizon3.ai's defenses and bridge the gap between technical TTPs and the business's security posture. This role significantly impacts our company's security by identifying and exploiting complex vulnerabilities in critical systems before adversaries can, safeguarding data and digital services.

Essential Functions

• Threat Modeling & Attack Planning: Conduct comprehensive threat modeling and risk assessments to identify high-value targets, analyze potential attack vectors, and prioritize red team objectives.
• Lead Red Team Operations: Design and execute end-to-end, objective-based red team operations targeting our production cloud and web environments, simulating real-world scenarios to test our defenses.
• Source Code Review: Perform deep, security-focused source code reviews (primarily in Python and JavaScript) to identify complex vulnerabilities like logic flaws, injection, and RCE.
• Cloud & Kubernetes Configuration Audits: Lead comprehensive security configuration audits of our AWS, Azure, GCP, Digital Ocean, and Kubernetes (K8s) environments, identifying exploitable misconfigurations, overly permissive IAM policies, and insecure network settings.
• CI/CD Pipeline Security: Assess and test the security of our CI/CD pipelines (e.g., Jenkins, GitLab CI, GitHub Actions, ArgoCD, Crossplane, etc.) to identify attack paths, secret management flaws, and vulnerabilities that could lead to supply chain attacks.
• Advanced Penetration Testing: Conduct in-depth penetration tests against critical web applications, APIs, and cloud-native services.
• Purple Teaming: Actively collaborate with engineering and defensive teams (Blue Team) in purple team exercises to validate findings and improve detection and response capabilities in real-time. Perform retesting for validation of mitigations or remediations.
• Tool & Methodology Development: Develop custom tooling, exploits, and automation scripts as required to bypass security controls. Develop and maintain red team methodologies, tools, and infrastructure.
• Threat Research: Stay abreast of the latest threat intelligence, vulnerabilities, and exploits; research and develop new exploitation techniques relevant to our technology stack.
• Reporting & Communication: Investigate, own, and report on vulnerabilities, exploit paths, and their business impact. Author clear, detailed reports and present findings to both technical and leadership audiences.

Requirements

We are seeking candidates with:

• 5+ years of hands-on experience in offensive security, with a demonstrable track record of leading complex web application and cloud penetration tests.
• Proven ability to read, review, and identify vulnerabilities in source code (especially Python and JavaScript).
• Deep, practical experience attacking and auditing cloud environments (e.g., AWS, GCP, Azure) including services like S3, EC2, RDS, IAM, Lambda, Azure Blob Storage, Google Cloud Storage, and Kubernetes clusters.
• One or more advanced, industry-recognized offensive security certifications: OSCP, OSWE, OSCE, CRTO, or GIAC (GCPN, GXPN).
• Expert-level knowledge of modern web application security, including the OWASP Top 10, API security, and common framework vulnerabilities.
• Strong proficiency in common offensive security tools (e.g., Burp Suite, Nmap) and C2 frameworks (e.g., Cobalt Strike, Sliver, Brute Ratel).
• Strong written and verbal communication, including technical documentation and the ability to explain technology to non-technical audiences.

Desired Skills

• Experience in a blue team, incident response, or system administration role.
• Experience with other cloud providers (e.g., GCP, Azure).
• Experience with OSINT, phishing, and social engineering campaigns.
• Familiarity with WAF technologies (e.g., AWS WAF, Akamai).
• Relevant cloud or K8s certifications (e.g., AWS Certified Security - Specialty, Certified Kubernetes Administrator (CKA)).

What Horizon3.ai Offers

• 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.
• Remote Work: We are a 100% remote company. Enjoy the flexibility to work in the way that supports you and brings out your best.
• Competitive Compensation: We offer competitive salary, equity and benefits including health, vision & dental insurance, flexible vacation, and generous parental leave.

Key skills/competency

• Offensive Security
• Cloud Penetration Testing
• Web Application Security
• Red Team Operations
• Source Code Review
• Kubernetes Security
• AWS/Azure/GCP Security
• CI/CD Security
• Vulnerability Research
• Purple Teaming