Senior Cybersecurity Analyst

Why Castelion, Why Now Castelion is moving incredibly fast to develop and deliver advanced defense systems at a time when execution matters more than ever. We believe focus, ownership, and excellence are decisive advantages - and we're building a world-class team to turn bold ideas into real capability. This is a rare opportunity to join at an early stage, where you'll have significant ownership, collaborate with exceptional teammates, and make a direct, measurable impact on our mission and the future of the company - regardless of your function. Senior Cybersecurity Analyst 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. Responsibilities • 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 Basic Qualifications • 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 (CrowdStrike, 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 Preferred Skills and Experience • 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 Additional Requirements • 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 Castelion offers a generous benefits package. Please refer to the bottom of our Careers page for more details. 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 for this job. Duties, responsibilities and activities may change at any time with or without notice. Additional Eligibility Requirements This position may require access to classified information or restricted U.S. Government sites, systems, or information, as determined by the Company and/or applicable U.S. Government requirements. If the position is so designated, your employment in the role may be contingent upon your ability to obtain and maintain the required U.S. Government security clearance or other government authorization, and to satisfy any citizenship or other eligibility requirements imposed by applicable law, regulation, executive order, or government contract requirements. You will be notified if and when such requirements apply. Affirmative Action/EEO Statement Castelion is an Equal Opportunity Employer. We are committed to providing equal employment opportunities to all applicants and employees without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, age, disability, genetic information, protected veteran status, or any other characteristic protected by applicable federal, state, or local law. Castelion is committed to providing reasonable accommodations to qualified individuals with disabilities throughout the application and hiring process. If you require a reasonable accommodation to complete an application, participate in the interview process, or otherwise participate in the hiring process, please contact hr@castelion.com. Requests for accommodation will be considered on an individual basis and handled in accordance with applicable law. Castelion is committed to fostering a workplace where employment decisions are based on qualifications, business needs, and the ability to perform the essential functions of the role, with or without reasonable accommodation. EAR/ITAR Requirements This position requires access to export-controlled information, and as such, employment (or hiring of a contractor) is contingent upon the candidate’s ability to access all applicable export-controlled information without additional export licensing being required by the Bureau of Industry and Security and/or the Directorate of Defense Trade Controls.