Cybersecurity Engineer / ISSE (onsite) with Security Clearance

Marathon TS is looking to hire a cleared Cybersecurity Engineer / ISSE to work onsite in Ashburn, VA on a newly awarded contract supporting the Department of Homeland Security Customs and Border Protection (Client CBP). The Cybersecurity Engineer / Information System Security Engineer (ISSE) will support cybersecurity engineering, security validation, vulnerability scan readiness, and ATO evidence activities for Unattended Ground Sensor (UGS) and operational technology systems.

This role supports Client-OpsTech lab validation efforts while also contributing to broader CBP cybersecurity, CSD coordination, and field-alignment activities. The position will support security reviews for UGS devices and supporting infrastructure, including embedded systems, sensors, cameras, receivers, base stations, network-connected devices, and related management platforms. The Cybersecurity Engineer / ISSE will collaborate stakeholders to help ensure security considerations are incorporated into lab validation, documentation, and future field-alignment planning.

Responsibilities: As a key member of the Client-OpsTech support team, the Cybersecurity Engineer / ISSE will support secure validation and documentation of operational technologies before broader field alignment or production-like implementation.

• Support cybersecurity engineering and ISSE activities for UGS and operational technology systems, with emphasis on lab validation, security readiness, and documentation.
• Support CSD VAT/Nessus scan readiness, including asset identification, scan scope, credential availability, scan limitations, vendor constraints, and device impact considerations.
• Support CSD SOC/Splunk readiness, including identification of available telemetry, log sources, logging limitations, monitoring requirements, and security-relevant events.
• Support firmware/software update validation, security update review, vendor release note review, checksum/hash validation, and security impact tracking.
• Document vulnerabilities, findings, limitations, remediation actions, compensating controls, and retest results in support of lab validation and ATO-related evidence.
• Provide security input to lab test plans, validation packages, acceptance recommendations, and Phase 2 handoff materials.
• Support configuration and change management by assessing whether proposed changes affect validated baselines, security posture, scanning requirements, monitoring, or field-alignment readiness.
• Coordinate with stakeholders to support secure integration and validation of UGS technologies.
• Support security-related documentation, including scan readiness checklists, security considerations, vulnerability tracking, and ATO evidence inputs.
• Provide security guidance to lab team members and support security audits, assessments, and evidence requests as needed.
• Support lab incident/security event handling by documenting security events, assessing validation impact, preserving evidence, and coordinating with appropriate stakeholders.

Qualifications

• Bachelor's degree in Cybersecurity, Information Technology, Computer Science, Engineering, or a related field; equivalent experience may be considered.
• Minimum of 5-7 years of experience in cybersecurity, security engineering, ISSE, vulnerability management, or security assessment roles.
• Experience supporting RMF, ATO, POA&M, security control evidence, vulnerability remediation, or continuous monitoring activities.
• Experience with vulnerability scanning tools such as Tenable Nessus or equivalent.
• Familiarity with SIEM/logging platforms such as Splunk and ability to identify useful telemetry/log sources.
• Experience assessing or supporting network-connected devices, embedded systems, operational technology, IoT, cameras, sensors, or field technology environments.
• Understanding of security hardening, firmware/software update validation, configuration baselines, change control, and risk documentation.
• Ability to document technical findings, limitations, test results, and security recommendations clearly for technical and program stakeholders.
• Ability to coordinate across cybersecurity, engineering, network, test, vendor, and program teams.
• Strong analytical, troubleshooting, and communication skills.
• Experience with Client/CBP environments, NIST, FISMA, RMF, or federal cybersecurity requirements preferred.

Certifications

• CompTIA Security+ or equivalent baseline cybersecurity certification required or strongly preferred.
• CISSP, CISM, CISA, CASP+, CySA+, or equivalent preferred.
• Tenable/Nessus, Splunk, vulnerability management, incident response, or continuous monitoring certifications are beneficial.
• Operational technology, IoT security, or industrial/field technology security training is a plus.

Clearance: Active Client EOD or DoD Secret or Top Secret clearance #cjjobs Marathon TS is committed to the development of a creative, diverse and inclusive work environment. In order to provide equal employment and advancement opportunities to all individuals, employment decisions at Marathon TS will be based on merit, qualifications, and abilities. Marathon TS does not discriminate against any person because of race, color, creed, religion, sex, national origin, disability, age or any other characteristic protected by law (referred to as "protected status ").