Information Systems Security Officer (ISSO)

The Mission Essential Group; Fairfax (VA); On-site; USD 120,000 - 135,000; Full time

Benefits offered by this job

Competitive salary

Medical, dental, vision insurance

Life and disability insurance

Paid time off

Retirement benefits

Job summary

The Mission Essential Group in Fairfax, VA is seeking an Information Systems Security Officer (ISSO) to support RMF activities, ATO processes, and continuous monitoring for DoD/IC systems. This role centers on applying security controls, vulnerability management, and risk assessment in a high-security environment.

Based at MEG’s Fairfax, VA headquarters, the ISSO collaborates with ISSMs, engineers, and assessors to ensure compliance, maintain authorization readiness, and implement security

Qualifications

• Active TS clearance.
• Bachelor’s degree in computer science, Information Systems, Cybersecurity, Information Technology.
• Minimum of five (5) years of Cyber Security experience.
• Minimum of three (3) years of RMF experience per NIST SP 800-37 Rev. 2.
• Working knowledge of NIST/NIST SP 800-60, SP 800-53 Rev. 5, CNSSI 1253 Rev. 5, DoDI 8510.01 and related processes.
• Experience supporting SIPRNet-connected systems and environments.
• Current CompTIA Security+ certification or equivalent DoD 8570/8140 baseline.
• Experience managing RMF packages and authorization activities using eMASS and/or Xacta.

Responsibilities

• Support RMF package development, security control implementation, assessment, continuous monitoring, and ATO processes using eMASS and/or Xacta.
• Verify changes that may impact security posture are documented and communicated to stakeholders.
• Serve as liaison between system owners, ISSMs, engineers, assessors, and cybersecurity stakeholders.
• Ensure day-to-day implementation, oversight, and compliance of multiple information systems.
• Lead meetings to identify, document, validate, and track cybersecurity requirements.
• Conduct vulnerability assessments and security scans using Nessus, SCAP, and approved tools.
• Implement and track corrective actions for incidents, vulnerabilities, or deficiencies.
• Develop and maintain Security Control Traceability Matrices (SCTMs).
• Stay current with federal and DoD cybersecurity policies and standards.

Skills

TS clearance

RMF

NIST SP 800-37

Windows Server

eMASS/Xacta

Cyber Security

CompTIA Security+

Education

Bachelor’s degree in computer science/Information Systems/Cybersecurity/IT

Tools

eMASS

Xacta

Nessus

SCAP Checker

Job description

Information Systems Security Officer (ISSO)

FAIRFAX, VIRGINIA

PostedOctober 02, 2026

DESCRIPTION

Position: ISSO

Clearance: TS/SIC

Salary Range: $120,000 - $135,000

Job Description:

The Mission Essential Group, LLC (MEG) is a premier service provider of information management solutions for complex, mission-critical needs. MEG has earned a reputation as an innovator and pioneer. Headquartered in Fairfax, VA, MEG employs professionals in offices located throughout the United States and around the world. MEG offers a competitive benefits package including a competitive salary; medical, dental, vision, life and disability insurance; paid time off; and retirement benefits.

MEG is a leading provider of Information Management system engineering, software development, information assurance, system sustainment and is the primary provider of technical support for the Integrated Broadcast Service (IBS) Enterprise. IBS is the worldwide Department of Defense (DoD) joint program for transporting intelligence, surveillance & reconnaissance (ISR) and targeting data to all levels of tactical and strategic operational users.

IBS provides global, 24/7, dissemination of time sensitive Indications & Warning and Force Protection data to Joint Warfighters and Collaborating Nation partners conducting military operations around the world. MEG serves a vital role in supporting the IBS Enterprise, providing continuity in skills crucial to support military operations. MEG integrates the talents and skills of team members to form an IBS Enterprise Support Services Team to provide world-class IBS customer support.

MEG provides innovative software tools, technical services, and rapid development of solutions to support end user requirements. As such our systems and products require are high level of quality and configuration management to ensure they meet and/or exceed customer expectations.

The ISSO serves as a key contributor to the organization's cybersecurity program, supporting the implementation of security controls, Risk Management Framework (RMF) activities, continuous monitoring, and Assessment and Authorization (A&A) efforts. This hands-on position requires a strong understanding of information assurance principles, cybersecurity best practices, and federal and DoD regulatory requirements to ensure the confidentiality, integrity, and availability of mission-critical information systems. The position is located at the company's headquarters in Fairfax, Virginia.

Duties and Responsibilities:

• Support Assessment and Authorization (A&A) activities, including RMF package development, security control implementation, assessment, validation, continuous monitoring, vulnerability management, POA&M tracking, and Authority to Operate (ATO) processes using eMASS and/or Xacta.
• Verify that system changes, upgrades, and modifications that may impact the security posture or authorization status of information systems are identified, documented, and communicated to appropriate stakeholders.
• Serve as the primary liaison between system owners, Information System Security Managers (ISSMs), engineers, assessors, and other cybersecurity stakeholders.
• Ensure the day-to-day implementation, oversight, continuous monitoring, and security compliance of multiple information systems.
• Lead and facilitate meetings with technical and functional subject matter experts to identify, document, validate, and track cybersecurity and compliance requirements.
• Conduct vulnerability assessments and security scans using tools such as Nessus, SCAP Compliance Checker, and other approved scanning solutions.
• Ensure appropriate protective and corrective actions are implemented and tracked when security incidents, vulnerabilities, or compliance deficiencies are identified.
• Perform risk assessments and assist with the identification, analysis, and mitigation of cybersecurity risks.
• Support the installation, configuration, and maintenance of hardware and software within secure computing environments.
• Apply security patches, updates, and configuration changes to maintain system compliance and reduce cybersecurity risk.
• Conduct cybersecurity investigations and develop reports, findings, recommendations, and corrective action plans as required.
• Develop and maintain Security Control Traceability Matrices (SCTMs) to map security requirements to DoD and NIST security controls.
• Research emerging technologies, cybersecurity threats, vulnerabilities, and industry best practices to support continuous improvement of security programs.
• Stay current with applicable federal and DoD cybersecurity policies, standards, regulations, and framework updates.
• Support audit activities, compliance reviews, and security inspections to ensure adherence to organizational and regulatory requirements.
• Assist with continuous monitoring activities, including vulnerability remediation, incident tracking, configuration management, and ongoing authorization support.

REQUIREMENTS

Minimum Qualifications:

• Active TS clearance
• Bachelor’s degree in computer science, Information Systems, Cybersecurity, Information Technology
• Minimum of Five (5) years of Cyber Security experience
• Minimum of three (3) years of experience applying the NIST Risk Management Framework (RMF) in accordance with NIST SP 800-37 Revision 2
• Working knowledge of federal and DoD cybersecurity standards and guidance, including NIST SP 800-60, NIST SP 800-53 Revision 5, CNSSI 1253 Revision 5, DoDI 8510.01 (RMF), and related authorization/accreditation processes.
• Experience supporting, administering, and maintaining SIPRNet-connected systems and environments.
• Strong knowledge and hands-on administration of Microsoft Windows server and workstation operating environments.
• Experience managing RMF packages and authorization activities using eMASS and/or Xacta workflow tools.
• Practical experience implementing and supporting cybersecurity technologies and controls, including encryption, data protection, identity and access management, privileged access management, vulnerability management, and continuous monitoring.
• Possession of a current CompTIA Security+ certification or equivalent DoD 8570/8140-approved baseline certification.

Desired Qualifications:

• Advanced certifications such as CISSP, CISM, CASP+, or GSLC are highly desirable.
• Experience with administration of Windows-based information systems

Mission Essential considers all applicants without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, disability, or veteran status. Mission Essential is an EEO/AA employer and a VEVRAA Federal Contractor.