Senior Cybersecurity Architect

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 Architect

We are seeking a
Senior Cybersecurity Architect
to lead the design and implementation of secure, resilient information security systems, monitoring, red/blue team activities, and more in support of regulated, compliance-heavy environments. This hands-on role is responsible for translating mission, system, and regulatory requirements into end-to-end cybersecurity solutions. These complete solutions should benefit from the candidate's experienced and thoughtful implementation of company policy, automation and enforcement of workflows/processes, and technical security measures.

Based in our Torrance, CA HQ, you'll lead efforts to build, maintain, and continuously improve our security and compliance posture across both local and remote sites. You'll collaborate with cross-functional teams—including IT, software development, operations, engineering, manufacturing, and legal—to ensure our security controls meet both technical and regulatory standards.

The ideal candidate brings deep technical expertise, strong systems thinking, hands-on experience, and is well-versed in frameworks like
NIST SP 800-171
,
CMMC
, or
ISO 27001
.

If you love solving hard problems under strict rules, thrive in high-stakes environments, and believe security should be a business enabler - not a blocker, this role is for you.

Responsibilities

• Define and implement security architectures aligned with Zero Trust principles, defense-in-depth, and least-privilege models
• Develop security reference architectures, patterns, and standards for enterprise and program-level systems
• Ensure cybersecurity is embedded across the full system lifecycle (requirements, design, development, test, deployment, sustainment)
• Design, implement, and maintain cybersecurity tools and systems, including firewalls, EDR, IDS/IPS, SIEM, and vulnerability scanners.
• Conduct threat modeling, security risk assessments, and vulnerability analyses.
• Proactively monitor security events, investigate suspicious activity, and respond to incidents with urgency and precision.
• Develop and maintain
  System Security Plans (SSPs),
  POA&Ms
  , and supporting documentation for audits and assessments.
• Partner with IT, engineering, Dev Sec Ops , and Program Security to integrate security into infrastructure and application design.
• Manage security patching cycles and lead remediation efforts based on risk assessments.
• Support audit, compliance, and risk management activities (e.g., NIST, CMMC, & others) and manage supply chain cybersecurity concerns.
• Conduct regular internal audits and readiness checks in preparation for external audits or DoD reviews.
• Serve as on-site cybersecurity expert for Torrance HQ and occasionally travel (5-10%) to other locations (TX/NM).

Required Qualifications

• 7-10+ years of hands-on experience in cybersecurity engineering, infrastructure security, or related fields.
• Strong technical background in network security, endpoint protection, access control, and vulnerability management.
• Proficiency with modern security tools (e.g., Crowd Strike, Palo Alto, Nessus, Splunk, Snort, etc.).
• Experience with incident response, malware analysis, and penetration testing.
• Demonstrated experience with cloud security (AWS, Azure, or GCP).
• Deep understanding of security principles, threats, and frameworks (e.g., cyber kill chain, MITRE ATT&CK, NIST, CIS Controls).
• Strong documentation, troubleshooting, and communication skills.
• Ability to thrive in fast-paced, high-pressure environments with competing priorities.
• Ability to pivot between analyst, threat hunter, and implementer roles with ease.
• Eligibility to keep and maintain a U.S. security clearance.

Preferred Qualifications

• Experience in regulated environments (DoD, aerospace, SCIFs).
• Active Security+, CISSP, CISM, CEH, or similar senior-level certification(s).
• Relevant experience with NIST 800-171, CMMC, DFARS, or other in relation to cybersecurity audit readiness.
• Experience with incident response, malware analysis, or penetration…