MSS Senior Security Specialist

ABOUT NOOKS Nooks is pioneering Classified-Infrastructure-as-a-Service (CIaaS) — designing, building, and operating Sensitive Compartmented Information Facilities (SCIFs) and other secured, classified environments for the defense and national security community. We work with the agencies, contractors, and mission-driven organizations that keep the nation safe, delivering the physical infrastructure that makes classified work possible. We’re growing fast, operating across multiple markets, and building a company that takes both the mission and the business seriously. About the Role Through our Managed Security Services (MSS) product line, we serve as the outsourced security function for a growing portfolio of defense tech companies and mission-driven organizations navigating the complex, opaque world of government security compliance. Our MSS team is the outsourced Facility Security Officer (FSO) behind that portfolio. As MSS grows, the hardest client work — first-time facility clearances (FCLs), foreign ownership questions, incidents and security violations, or DCSA security  reviews — needs someone who can own it end-to-end without a manager in the room. As a Senior Security Specialist, you will carry the most complex accounts in our active portfolio, drive high-touch client onboarding, and set the quality bar for the specialists around you, reporting to the Group Lead as a team contributor. This is a senior delivery seat, not a people-management seat — people management begins at Group Lead. You support under each client's appointed FSO; MSS staff act as Assistant FSOs (AFSOs) to manage operational execution, and not as the client’s appointed FSO. In MSS, we move fast. Managing security operations across a multi-client portfolio means you’ll handle multiple customer environments simultaneously, context-switch between priorities, and adapt quickly when urgent client or government needs arise. We’re looking for a proactive problem-solver who thrives in a dynamic environment, balances competing deadlines effortlessly, and is ready to lean in wherever the team needs them to keep our client portfolio compliant and mission-ready.  Key Responsibilities Multi-Client Portfolio & Compliance Ownership Manage end-to-end industrial security operations for a portfolio of complex, high-touch client accounts, executing personnel security actions in DISS and NBIS, visit authorizations, security briefings, and roster maintenance under each client’s appointed FSO. Guide clients through the FOCI process by assisting with SF-328 disclosures and reviewing DCSA-issued risk mitigation documentation (including Special Board Resolutions, TCPs, ECMPs, etc). Interpret complex 32 CFR Part 117 (NISPOM) requirements to deliver clear, defensible compliance guidance tailored to fast-growing, non-traditional defense contractors. Act as the primary internal escalation point for Security Specialists facing complex casework before issues are elevated to the Group Lead. Incidents/Violations, Government Interaction, & Client Onboarding Lead end-to-end response for adverse information, security violations, and reportable incidents, coordinating government notifications and mitigation directly with DCSA under the client's FSO authority. Drive new client onboarding from initial gap assessment and KMP alignment through program stand-up, establishing compliant baseline security operations before transitioning routine maintenance to Security Specialists. Prepare clients for annual DCSA Continuous Monitoring and Security Reviews, leading pre-audit self-inspections and driving corrective action plans to full closure. Quality Control, Peer Review & Mentorship Review and sign off on high-impact client deliverables, eAPP packages, and routine system actions in  DISS/NBIS completed by Security Specialists, upholding audit-readiness and accuracy across all accounts. Mentor Security Specialists on advanced compliance workflows, client relationship management, and DCSA interactions without carrying direct people-management responsibilities. Establish and enforce quality assurance standards across all external client communications, security documentation, and official filings.  Operational Excellence & Product Feedback  Standardize recurring client challenges into reusable templates, playbooks, standard operating procedures (SOPs), and compliance checklists for the broader MSS team.  Feed recurring client needs and tooling gaps to the Group Lead and Digital. Refine onboarding and self-inspection approaches so the team runs them consistently across clients. What Success Looks Like in This Role You independently run a portfolio of our most complex client accounts — guiding them through first-time facility clearances, FOCI mitigations (like TCPs or ECMPs), and high-priority incident reporting — ensuring seamless DCSA reviews without last-minute scrambles. When a client faces a reportab