Information Systems Security Engineer (ISSE) Linux/RHEL

About the role

The Opportunity:
We are seeking a highly motivated, Linux-focused Information Systems Security Engineer (ISSE) to support the security, accreditation, and continuous monitoring of mission-critical systems operating within classified environments.
The ideal candidate combines cybersecurity engineering expertise with hands-on Red Hat Enterprise Linux (RHEL) administration skills. This position requires an individual comfortable working directly with Linux systems to implement security controls, troubleshoot configurations, remediate vulnerabilities, and support Risk Management Framework (RMF) compliance.
Working alongside systems engineers, software developers, and cybersecurity professionals, you will help design, implement, and maintain secure solutions supporting critical national security missions.
This position requires onsite support 100% of the time in Sterling, VA. Domestic and international travel opportunities may be available.
Responsibilities:
Perform hands-on security engineering, configuration, troubleshooting, and hardening of Red Hat Enterprise Linux (RHEL) systems
Implement, validate, and maintain DISA STIG compliance, including executing SCAP scans, analyzing findings, and remediating security vulnerabilities
Troubleshoot Linux security configurations involving SELinux, SSH, permissions, authentication, system services, and networking
Lead and support Assessment and Authorization (A&A) activities to achieve and maintain Authorization to Operate (ATO) under the Risk Management Framework (RMF)
Develop and maintain security documentation, including System Security Plans (SSPs), Security Assessment Reports (SARs), Security Control Traceability Matrices (SCTMs), and Plans of Action and Milestones (POA&Ms)
Conduct security assessments and continuous monitoring activities aligned with ICD 503, NIST 800-53, CNSSI, and applicable DoD requirements
Collaborate with systems, network, software, and DevOps engineers to integrate security requirements throughout the System Development Life Cycle (SDLC)
Evaluate system architectures, infrastructure changes, and software configurations to identify security risks and recommend mitigations
Develop Bash or Python scripts to automate security compliance, vulnerability assessments, and routine administrative tasks.
Qualifications:
Required: 
Required
5+ years of combined experience in cybersecurity engineering, information assurance, Linux systems administration, or related technical disciplines
Minimum 2 years of hands-on Linux administration experience, preferably with RHEL 8/9
Practical Linux command-line proficiency, including filesystem management, permissions, user administration, package management (DNF/YUM), systemd services, log analysis, SSH, and basic network troubleshooting
Experience implementing Linux DISA STIGs, executing SCAP scans, and performing vulnerability remediation
Working knowledge of Linux security technologies, including SELinux, firewalld, authentication, and access controls
Experience with Bash scripting and/or Python for system administration or security automation
Strong understanding of RMF, ICD 503, NIST 800-53, and the ATO lifecycle
DoD 8570/8140 IAT Level II certification (Security+ CE, CySA+, SSCP, or equivalent applicable certification)
Bachelor's degree in a technical discipline or equivalent relevant experience
Active Top Secret clearance with SCI eligibility.
Desired:
Red Hat Certified System Administrator (RHCSA) or Red Hat Certified Engineer (RHCE) certification.
Experience supporting RHEL systems in classified, disconnected, or air-gapped environments.
Familiarity with Puppet, Ansible, Red Hat Satellite, or Red Hat Identity Management (IdM/FreeIPA).
Experience with ACAS, Nessus, SCAP Compliance Checker, or similar vulnerability assessment tools
Experience with Git, GitLab, DevSecOps, and automated compliance solutions
Experience supporting Cross Domain Solutions (CDS) or other highly secure mission systems
Advanced cybersecurity certifications such as CISSP or CASP+

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What You Can Expect:

 A culture of integrity.

At CACI, we place character and innovation at the center of everything we do. As a valued team member, you’ll be part of a high-performing group dedicated to our customer’s missions and driven by a higher purpose – to ensure the safety of our nation.

An environment of trust.

CACI values the unique contributions that every employee brings to our company and our customers - every day. You’ll have the autonomy to take the time you need through a unique flexible time off benefit and have access to robust learning resources to make your ambitions a reality.

A focus on continuous growth.

Together, we will advance our nation's most critical missions, build on our lengthy track record of business success, and find opportunities to break new ground — in your career and in our legacy.

Pay Range:

There are a host of factors that can influence final salary including, but not limited to, geographic location, Federal Government contract labor categories and contract wage rates, relevant prior work experience, specific skills and competencies, education, and certifications. Our employees value the flexibility at CACI that allows them to balance quality work and their personal lives. We offer competitive compensation, benefits and learning and development opportunities. Our broad and competitive mix of benefits options is designed to support and protect employees and their families. At CACI, you will receive comprehensive benefits such as; healthcare, wellness, financial, retirement, family support, continuing education, and time off benefits.

The proposed salary range for this position is:

$86,600 - $181,800

CACI is an Equal Opportunity Employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, pregnancy, sexual orientation, age, national origin, disability, status as a protected veteran, or any other protected characteristic.