ISSE – RMF & Linux/RTOS Security Engineer (Onsite)

ManageXR; Chantilly (VA); On-site; USD 110,000 - 160,000; Full time

Job summary

ManTech in Chantilly, VA is seeking an Information Systems Security Engineer to join our security team onsite, with an option for San Diego, CA. The role focuses on RMF, security engineering, and the cybersecurity lifecycle to design and implement security controls across Linux, RTOS, and Windows environments.

You will perform hands-on hardening, log analysis, vulnerability management with Nessus, Trellix, and SIEM tools like Splunk/ELK, maintain RMF artifacts in eMASS, and support AO decisions.

Qualifications

• 2+ years in cybersecurity engineering, RMF, or system administration.
• Active DoD 8570/8140 IAT Level II certification (e.g., Security+ CE, CySA+, CISSP).
• Experience with Linux and RTOS (e.g., QNX, VxWorks) environments.
• Hands-on with Nessus and Trellix; familiarity with SIEM tools.
• Experience maintaining RMF artifacts in eMASS.

Responsibilities

• Assist design and integration of security controls into systems throughout the SDLC.
• Support RMF execution and system categorization with documentation and diagrams.
• Perform hardening, log analysis, and remediation on Linux/RTOS and Windows.
• Operate vulnerability scanners and deploy security tooling across endpoints.
• Maintain RMF artifacts in eMASS and support AO decisions.

Skills

RMF experience

Security engineering

Linux admin

RTOS knowledge

Windows environments

Scripting (Bash/Python/PowerShell)

eMASS familiarity

Education

Bachelor's degree in IT/CS/Cybersecurity/CE

High School Diploma/GED + 6+ years experience

Tools

Nessus

Trellix endpoint security

Splunk

ELK / Elasticsearch

eMASS

Job description

ManTech in Chantilly, VA is seeking an Information Systems Security Engineer to join our security team onsite, with an option for San Diego, CA. The role focuses on RMF, security engineering, and the cybersecurity lifecycle to design and implement security controls across Linux, RTOS, and Windows environments.

You will perform hands-on hardening, log analysis, vulnerability management with Nessus, Trellix, and SIEM tools like Splunk/ELK, maintain RMF artifacts in eMASS, and support AO decisions.