Cyber Security Engineer / ISSE Lead Security Engineering for MissionCritical Systems

Leidos is seeking a Cyber Security Engineer / Information Systems Security Engineer (ISSE) to support a highvisibility missionessential enterprise this role youll apply deep security engineering expertise to design assess and harden complex systems while guiding them through the full Risk Management Framework (RMF) lifecycle. If you thrive at the intersection of technical engineering cybersecurity strategy and accreditation excellence this is where your impact will be felt immediately.

Youll collaborate with accreditation authorities system owners and engineering teams to ensure systems achieve and maintain Authorization to Operate (ATO) while meeting the highest security standards.

What Youll Do

As a senior security engineer youll shape the security posture of missioncritical applications and lead the engineering of RMF artifacts across a largescale enterprise environment.

Your responsibilities include:

• Supporting missioncritical applications through the full ATO lifecycle in alignment with customer security policies

• Leading security engineering efforts and contributing to system design with a focus on secure architecture

• Ensuring ATO packages adhere to RMF and DoD security guidelines by working closely with technical leads developers and system owners

• Providing expert ISSE guidance across engineering tasks and projects

• Defining system functions information types operating environments and security requirements

• Producing security artifacts and evidence for RMF control validation

• Reviewing and tailoring security controls to ensure adequate protection

• Determining assurance measures to meet system assurance requirements

• Designing and implementing security controls and best practices including Zero Trust Architecture

• Conducting A&A activities and coordinating with DAO representatives and security teams

• Creating and updating RMF documentation and artifacts in eMASS

• Reviewing system audit logs and taking corrective action when needed

• Performing security monitoring audits and control assessments using enterprise tool suites

• Delivering technical briefings and TEMs to communicate security concepts to nontechnical stakeholders

• Developing security assessment criteria to ensure development teams meet A&A requirements

• Ensuring compliance with encryption standards and secure communications

• Staying ahead of emerging security trends and technologies to support future mission needs

• Mentoring team members and supporting project execution across the security engineering team

Required Qualifications & Skills

You bring deep technical expertise strong security engineering instincts and the ability to lead complex accreditation efforts.

• Active DoD TS/SCI clearance

• Current DoD 8140compliant security certification; ability to obtain CE certification within 6 months

• 10 years of experience in software engineering system design configuration management integration testing or information system engineering

• 5 years of experience in system security analysis secure system design or protocol/interface standards

• Experience with Assessment & Authorization (A&A) for multiple security applications

• Experience preparing SSPs risk assessments SOPs and contingency plans

• Demonstrated experience creating and validating RMF security control evidence

• Experience hardening Windows and Linux systems (ports protocols security groups patching)

• Working knowledge of RHEL 9 and Windows Server 2019/2022

• Ability to work in an Agile environment using sprints and Jira boards

• Experience applying Agile methodologies to security engineering workflows

• Proficiency with enterprise scanning tools such as Tenable Burp Suite Defender for Endpoint ACAS ESS and Tanium

• Strong communication skills for both technical and nontechnical audiences

• Ability to manage multiple tasks in a dynamic environment

Preferred Qualifications

These skills will help you stand out:

• Experience with Security Onion

• Familiarity with backend security analysis tools such as Suricata Yara Sigma Elasticsearch Logstash Kibana Elastic Fleet PCAP OSquery and Zeek

• Experience with Splunk Elasticsearch SIEM and SOAR platforms

Why This Role Matters

As an ISSE you are a key architect of mission security. Your work ensures that critical systems remain secure compliant and resilient against evolving threats. Youll shape the security engineering strategy for a major enterprise program while mentoring others and driving innovation across the organization.

If youre looking for comfort keep scrolling. At Leidos we outthink outbuild and outpace the status quo because the mission demands it. Were not hiring followers. Were recruiting the ones who disrupt provoke and refuse to fail. Step 10 is ancient history. Were already at step 30 and moving faster than anyone else dares.

Original Posting:

Pay Range:

The Leidos pay range for this job level is a general guideline onlyand not a guarantee of compensation or salary. Additional factors considered in extending an offer include (but are not limited to) responsibilities of the job education experience knowledge skills and abilities as well as internal equity alignment with market data applicable bargaining agreement (if any) or other law.