Information System Security Engineer

MANTECH•Chantilly, VA

23h•$91,600 - $153,800•Onsite

About The Position

MANTECH is hiring a motivated, customer-oriented Information Systems Security Engineer (ISSE) to support its team in Chantilly, Virginia. The position is onsite and may optionally be located in San Diego, California. The ISSE supports Risk Management Framework (RMF), security engineering, and cybersecurity lifecycle activities, focusing on security control design and implementation, system hardening, technical remediation, continuous monitoring, and security-stack operations. The work emphasizes Linux systems and real-time operating systems (RTOS), with supporting knowledge of Windows environments. Applicants must hold a current or active Top Secret security clearance.

Requirements

Bachelor’s degree in IT, Computer Science, Cybersecurity, Computer Engineering, or a related field with at least 2 years of relevant cybersecurity, system administration, or RMF experience; or a high school diploma/GED with at least 6 years of cybersecurity engineering, system administration, or RMF experience.
At least 2 years of hands-on experience configuring, hardening, or troubleshooting Linux operating systems, with exposure to RTOS (such as QNX or VxWorks) or Windows environments.
Active DoD 8570/8140 IAT Level II certification, such as CompTIA Security+ CE, CySA+, SecurityX, or CISSP.
Hands-on experience or working knowledge of Nessus vulnerability scanners and Trellix endpoint security tools.
Experience or training with eMASS.
Familiarity with Bash, Python, or PowerShell for basic task automation, configuration management, or compliance checking.
Current or active Top Secret security clearance.
Able to remain stationary 50% of the time.
Occasionally move about inside the office to access file cabinets, office machinery, and similar items.
Frequently communicate with co-workers, management, and customers and exchange accurate information.

Nice To Haves

Hands-on experience installing, configuring, or operating Splunk, Elasticsearch/Kibana (ELK), or another enterprise log analytics platform.
Understanding of PL2 versus PL3 security baselines, trust boundaries, and segmentation concepts.
Active industry certifications such as CompTIA Linux+, CGRC, IAT Level III SecurityX (CASP+), or CISSP.
Experience integrating security into the SDLC or using configuration management tools such as Ansible, Puppet, or Chef for STIG automation.

Responsibilities

Assist with or lead the design and integration of technical security controls into system hardware, software, and networking architectures throughout the SDLC.
Work on a technical security engineering team implementing and maintaining compliant security architectures across complex platforms.
Support RMF execution and system categorization by defining authorization boundaries and preparing network diagrams, hardware/software inventories, data-flow documentation, and cryptographic mapping.
Configure, harden, analyze logs, and remediate Linux and RTOS environments, enforcing DISA STIGs through automated scripting.
Operate, configure, and maintain Nessus vulnerability scanners; collaborate with ISSOs to analyze scan results and determine remediation pathways.
Deploy, configure, and troubleshoot Trellix endpoint security tools to enforce media/device control policies and host-based defenses.
Support and maintain enterprise log ingestion and SIEM platforms such as Splunk or Elastic (ELK) for centralized auditing and continuous monitoring.
Maintain accurate RMF artifacts in eMASS, including the System Security Plan (SSP), POA&M, and supporting technical evidence for Authorizing Official (AO) decisions.