MSS Senior Security Specialist

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 reportable incident, security violation, or government review, you handle the interaction from start to finish under the client’s appointed FSO, earning the trust of both client leadership and DCSA. The Security Specialists whose work you review produce higher-quality, audit-ready deliverables with fewer errors over time because your sign-off serves as active coaching. New clients you onboard reach a steady operational state faster because you establish a compliant, scalable foundation from day one. 

Cross-Functional Expectations

You will work within the MSS team — mentoring Security Specialists and partnering with your Group Lead and the Senior Director of Solutions — as all MSS customer work is owned and delivered within MSS. Your collaboration will help balance portfolio workloads, address capacity constraints early, and share best practices across the team. Externally, you serve as the trusted operational bridge between client executives  (such as appointed FSOs and SMOs) and government officials, translating complex regulatory requirements into practical, business-friendly execution. 

The Skillset

• 5+ years of personnel or industrial security experience, with a track record of owning client or program security work independently.
• Mastery of DISS and NBIS and working depth in 32 CFR Part 117 (NISPOM), including self-inspections, incidents, and reporting.
• Direct experience interacting with DCSA — reviews, reportable incidents, or violation response.
• Sound judgment on gray-area security questions, with the ability to document a defensible rationale.
• Clear communication and the credibility to review peers' work and represent Nooks to client leadership.

Preferred:

• DCSA FSO Program Management certification and Security Professional Education Development (SPeD) Security Fundamentals Professional Certification (SFPC).
• Experience with first-time facility clearance (FCL) sponsorship or Foreign Ownership, Control, or Influence (FOCI)-mitigated clients.
• Prior work in a defense-tech, startup, or multi-client services environment.

Eligibility & Clearance

Candidates must be authorized to work in the United States. An active Secret security clearance is required.