Senior Cybersecurity Analyst

Castelion is moving incredibly fast to develop and deliver advanced defense systems at a time when execution matters more than ever. We believe focus and technical excellence are decisive advantages – and we are building a team that can deliver real capability, not just concepts.

This is a rare opportunity to join at an early stage, where your work will directly shape critical systems, influence major technical decisions, and have immediate, real-world impact.

We are seeking an experienced Senior Cybersecurity Analyst to join our team. This role will be responsible for protecting sensitive systems, data, and infrastructure critical to national security. The ideal candidate will have expertise in threat detection, SOC operations, incident response, and compliance frameworks specific to the defense industrial base.

• Lead 24/7 security monitoring efforts using SIEM platforms and advanced threat detection tools
• Analyze security events, identify potential threats, and coordinate incident response activities
• Identify vulnerabilities and recommend remediation strategies for complex environments
• Analyze malware, APT tactics, and threat actor behavior
• Perform threat hunting activities to proactively identify sophisticated adversaries
• Conduct forensic analysis of security incidents involving classified and sensitive systems
• Contribute to compliance with NIST 800-171, CMMC, DFARS, ITAR, and other DoD requirements
• Contribute to and/or maintain security documentation including internal documentation, policies and procedures, incident reports, and audit artifacts
• Configure and maintain security tools including IDS/IPS, EDR, DLP, and vulnerability scanners
• Support secure architecture reviews across the organization
• Mentor junior analysts and contribute to team skill development
• Coordinate with IT, engineering, manufacturing, and program teams on security initiatives
• Participate in threat intelligence sharing with government and industry partners

• 3+ years of experience in cybersecurity, information security, or related technical security roles
• Hands‑on experience with security operations, incident response, and threat analysis
• Expert knowledge of security tools: SIEM (Splunk, QRadar, Sentinel), EDR (Crowd Strike, Carbon Black), IDS/IPS
• Deep knowledge of MITRE ATT&CK framework and adversary tactics, techniques, and procedures
• Familiarity with threat intelligence platforms and OSINT techniques
• Experience protecting Controlled Unclassified Information (CUI)
• Experience operating within aerospace, defense, national security, government contracting, or highly regulated technical environments
• Strong understanding of network protocols, operating systems (Windows, Linux), and cloud environments
• Experience as a member of incident response protocols, vulnerability management, and security operations functions
• Proficiency in scripting/automation
• U.S. Person status required to comply with ITAR regulations
• Ability to obtain and maintain a U.S. security clearance

• Experience supporting defense manufacturing or operational technology (OT/ICS) environments
• Experience securing embedded systems, avionics, autonomous systems, or weapon systems
• Experience at high‑growth startups or scaling organizations
• Hands‑on experience implementing SIEM and SOAR operations
• Experience with CMMC 2.0, NIST SP 800-171, DFARS 252.204‑7012/7020/7021, ITAR, and related defense compliance requirements
• Industry certifications such as Security+, CEH, CISA, GIAC, or equivalent
• Degree in Cybersecurity, Computer Science, Engineering, or related field

• Ability to put in extended hours, including evenings and weekends, when required to meet aggressive timelines
• This role is based in Torrance, CA and requires full‑time onsite presence

All full‑time employees are granted meaningful long‑term equity, sharing in the company's significant growth trajectory. We offer four (4) weeks of paid time off, ten (10) company‑paid holidays, and comprehensive health benefits - including 100% employee‑covered medical and strong dependent coverage, along with dental and vision…