Senior Cybersecurity Analyst

About the role

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.

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

Requirements

• 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
• 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

Skills

• 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