Information System Security Officer (ISSO)
Castelion — Tracked from its manatal job board
About the role
About Castelion
Castelion is bringing a new approach to defense development and production: one that focuses on short, iterative design cycles, rapid testing in development, and modern commercial manufacturing strategies for production at scale. We're designing, building, and testing next generation long range strike weapons systems to give America and its Allies a definitive edge and deter future conflicts.
Information System Security Officer (ISSO)
Castelion is seeking a classified cyber assurance practitioner to assist the ISSM in driving the Castelion classified cyber assurance program forward. The program focuses on three major areas:
Assessment: Assessing the state of the classified cyber assurance program against industry standards, requirements (contractual and regulatory), and organizational needs.
Governance: Managing and spearheading governance of the classified cyber assurance program to interpret and drive implementation of industry standards, requirements (contractual and regulatory), and organizational needs.
Communications: Be "the face" of classified cyber assurance program to both internal and external stakeholders (e.g. customer, regulatory, government and supplier entities).
The successful candidate will assist in driving the classified assurance team to ensure Castelion delivers on customer requirements, reduces risk, and ensures mission success. We are a fast paced, multi-tasking, highly dynamic work environment with high degrees of autonomy and accountability.
Responsibilities
Assist the ISSM in the completion of the RMF A&A lifecycle process for assigned Castelion classified information systems
Ensure compliance with existing regulatory, policy, and contractual requirements as they pertain to Castelion classified information systems
Able to identify, triage, and implement new regulatory and contractual requirements into both broad and specific applications
Keep apprised of emerging community practices, risks, and threats
Plan, prepare for, schedule and coordinate audits, assessments, and tests
Identify, evaluate, and select various automation, assessment, and management tool sets to drive effectiveness and efficiencies
Provide advanced knowledge of Nessus, Splunk and Security Center tools
Provide advanced knowledge of Service Now (SNOW), eMASS, and other GRC tools
Build and maintain positive relationships with internal stakeholders, contractual partners, and government customers
Successfully further Castelion objectives and initiatives
Responsible for auditing all classified information systems
Deliver user briefings and agreements in accordance with government requirements
Create and maintain data transfer/assured file transfer policies and logs
Assist ISSM in record maintenance of all classified network equipment
Basic Qualifications
Bachelor's degree; OR 3+ years of experience managing cyber assurance for classified computer systems/networks in lieu of a degree
1+ years of experience in cyber assurance
Preferred Skills and Experience
Demonstrated experience with NRO A&A processes and the JSIG A&A processes
Subject matter expertise in the RMF 7 step process
Experience working within highly technical and demanding teams and environments
Experience with obtaining ATO(s) for networks, weapon systems, and satellite systems
Demonstrated experience with COMSEC procedures and practices
Exceptional written and verbal communication skills
Exceptional organizational skills
Demonstrated project management skills, and continued track record of getting things done quickly with high quality
Demonstrated record for providing unique and/or novel solutions
Demonstrated record of integrating with I.T. and product security functions
Ability to perform within mission and time constrained environments
High comfort with and acceptance of performing individual contributor functions/tasks
Additional Requirements
Must be able to work extended hours and/or weekends as needed
Ability to travel both locally and domestically
DoD IAM Level III eligibility based on active certifications
Counterintelligence (CI) scope polygraph (full-scope or lifestyle also acceptable), or ability to successfully complete
This position is based in Torrance, CA and requires being onsite - remote work not considered
Active Top Secret clearance with SCI eligibility.
Leadership Qualities
Bias to Action and Creative Problem Solving . Desire and experience questioning assumptions in ways that lead to break through ideas that are ultimately implemented. Successfully bring in applicable processes/concepts/materials from other industries to achieve efficiency gains. Ability to personally resolve minor issues in development without requiring significant support.
High Commitment, High Initiative . A successful candidate will have a genuine passion for Castelion's mission and consistently look for ways to contribute to the company's technical goals and prevent hardware blockers. Ability to work in a fast paced, autonomously driven, and demanding atmosphere. Strong sense of accountability and integrity.
Clear Communicator. Proactively communicates blockers. Trusted in previous roles to be voice of company with regulators, suppliers, gate keepers and customers. Capable of tactfully managing relationships with stakeholders to achieve company-desired outcomes without compromising relationships. Emails, IMs and verbal interactions are logical, drive clarity, and detailed enough to eliminate ambiguity.
ITAR Requirements
To conform to U.S. Government export regulations, applicant must be a (i) U.S. citizen or national, (ii) U.S. lawful, permanent resident (aka green card holder), (iii) Refugee under 8 U.S.C. § 1157, or (iv) Asylee under 8 U.S.C. § 1158, or be eligible to obtain the required authorizations from the U.S. Department of State.
Employment with Castelion is governed on the basis of competence and qualifications and will not be influenced in any manner by race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, sexual orientation, gender identity, marital status, mental or physical disability or any other legally protected status.
All employees are granted long-term stock incentives as part of their employment as Castelion. All employees receive access to comprehensive medical, vision, and dental insurance, and the company offers four weeks of paid time off per year.
What the index says about this role
- First seen by JobLarper — Aug 2, 2026, 6 days ago. Older postings collect hundreds of applicants — a tailored résumé matters more the longer a role has been live.
- Castelion is hiring actively — 98 open roles indexed.
Derived from the 26,996 roles JobLarper indexes daily from official company boards — not from the job description above.
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