Senior DoD ISSM — RMF/ATO Leadership

Cornerstone Defense LLC; Odenton (MD); On-site; USD 145,000 - 165,000; Full time

Benefits offered by this job

Medical plan

Dental plan

Vision plan

401(k)

HSA options

FSA options

Life insurance

Disability insurance

Tuition reimbursement

Training programs

Perks at work

Referral program

Leads generation

529 plan

Fitness reimbursement

Travel assistance

Lifelock benefit

Financial & legal services

Job summary

Cornerstone Defense LLC is seeking a Senior Information System Security Manager to oversee the cybersecurity posture for DoD systems in Odenton, MD. You will own the RMF lifecycle, ensure ATO readiness, and develop robust security documentation in alignment with DoD standards.

The role requires active DoD Secret clearance, substantial RMF experience, and the ability to coordinate across engineering and program teams to maintain secure, compliant environments.

Qualifications

• Bachelor’s degree with 8+ years of experience or Master’s degree with 6+ years (additional experience may substitute for education).
• CISSP, CISM, or equivalent senior‑level cybersecurity certification.
• Detailed knowledge of DoD cybersecurity policies, frameworks, and standards such as NIST 800‑53, RMF, FISMA, ICD 503, and JSIG.
• Extensive experience maintaining ATOs for DoD enterprise systems.
• Experience with system security engineering, risk management, and vulnerability assessment methodology.
• Strong understanding of network security principles and common cyber tools (firewalls, IDS/IPS, SIEM, endpoint protection).
• Ability to operate independently and collaboratively across cross‑functional teams.
• Excellent communication skills with experience preparing and presenting detailed cybersecurity reports.

Responsibilities

• Manage the full RMF lifecycle to achieve and maintain system Authority to Operate (ATO).
• Provide ISSM support across FISMA, certification, and accreditation requirements.
• Conduct recurring assessments of security controls and documentation within eMASS and PPSM to maintain accuracy, compliance, and audit readiness.
• Manage whitelist records and address vulnerabilities identified through IAVMS scans; develop and track POA&Ms.
• Maintain eMASS control records and POA&Ms in alignment with ATO conditions, approval requirements, and remediation timelines.
• Coordinate cybersecurity activities for interim and final authorization to test and operate—ensuring assessments, mitigation planning, patch validation, and reporting are executed effectively.
• Develop and deliver cybersecurity documentation including test plans, test reports, implementation plans, STIG/configuration artifacts, vulnerability assessment reports, and full authorization package materials.
• Lead cybersecurity governance activities—managing system architectures, security requirements, protection plans, IAVA actions, and IA compliance objectives.
• Prepare documentation, evidence, and briefings for DISA OAB reviews and support the team throughout the review and adjudication process.

Skills

CISSP

CISM

NIST 800-53

RMF

FISMA

JSIG

Strong communication

Independent work

Cross-functional collaboration

Education

Bachelor’s degree with 8+ years of experience

Master’s degree with 6+ years of experience

Tools

Firewalls

IDS/IPS

SIEM

Endpoint protection

Job description

Cornerstone Defense LLC is seeking a Senior Information System Security Manager to oversee the cybersecurity posture for DoD systems in Odenton, MD. You will own the RMF lifecycle, ensure ATO readiness, and develop robust security documentation in alignment with DoD standards.

The role requires active DoD Secret clearance, substantial RMF experience, and the ability to coordinate across engineering and program teams to maintain secure, compliant environments.