The mission of the DHS Chief Information Security Officer Directorate (DHS CISOD) is to support the Department’s implementation of all applicable regulatory requirements—including the Federal Information Security Modernization Act (FISMA), relevant OMB circulars, Executive Orders, Federal laws, directives, policies, and regulations—while providing the Department of Homeland Security (DHS) a secure and trusted computing environment. Information security is an essential business function, critical to enabling DHS to conduct its operations and deliver service to the public.

Leidos has a critical need for a Senior National Security Systems (NSS) Assessor to support the DHS Cyber Security Support Service Program. This role will execute security control assessments (SCAs) and provide risk analysis across highly sensitive NSS environments, ensuring compliance with CNSS, NIST, and DHS standards. The Senior NSS Assessor will deliver expert guidance to government stakeholders and contribute to the continuous improvement of cybersecurity posture for mission-critical systems.

Primary Responsibilities

Conduct security control assessments (SCAs) in accordance with the NIST Risk Management Framework (RMF) and CNSS policies, standards, and guidelines.Provide validation, analysis, and documentation of assessments for DHS NSS systems, applications, and appliances.Develop, maintain, and improve formal NSS assessment and compliance CONOPS and SOPs.Evaluate and update cybersecurity risk indicators, including risks from emerging threats and vulnerabilities.Deliver risk recommendations and track remediation through POA&Ms and continuous monitoring processes.Author white papers and reports to identify trends, adversary activity, and systemic risks impacting DHS NSS.Support NSCD compliance engagements, engineering review boards, configuration control boards, and C-SCRM efforts.Document lessons learned and provide training and guidance to NSS stakeholders.

Required Qualifications:

Active Secret clearance.Bachelor’s degree and at least 8 years of related experience or Master’s degree with at least 6 years of related experience.Strong knowledge of DHS IA policies, CNSS guidance, NIST RMF, FISMA, and related standards.Demonstrated experience with audits, compliance, and IT security review processes.Excellent written and verbal communication skills with proven ability to brief senior leadership.U.S. citizenship required.

Preferred Qualifications:

Prior DHS IT security or audit experience.Experience supporting NSS or other high-security national mission environments.Familiarity with FedRAMP, FIPS-140-2, and other federal compliance frameworks.

At Leidos, we don’t want someone who "fits the mold"—we want someone who melts it down and builds something better. This is a role for the restless, the over-caffeinated, the ones who ask, “what’s next?” before the dust settles on “what’s now.”

If you’re already scheming step 20 while everyone else is still debating step 2… good. You’ll fit right in.

Original Posting:September 8, 2025

For U.S. Positions: While subject to change based on business needs, Leidos reasonably anticipates that this job requisition will remain open for at least 3 days with an anticipated close date of no earlier than 3 days after the original posting date as listed above.

Pay Range:Pay Range $104,650.00 - $189,175.00

The Leidos pay range for this job level is a general guideline only and not a guarantee of compensation or salary. Additional factors considered in extending an offer include (but are not limited to) responsibilities of the job, education, experience, knowledge, skills, and abilities, as well as internal equity, alignment with market data, applicable bargaining agreement (if any), or other law.