Senior ISSE/Penetration Tester TS/SCI Polygraph

Senior ISSE/Penetration Tester Leidos has an exciting and challenging opportunity for a Senior ISSE/Penetration Tester in our Intel Sector’s Cyber & Analytics Business Area (CABA). Our talented team is at the forefront in Security Engineering, Computer Network Operations (CNO), Mission Software, Analytical Methods and Modeling, Signals Intelligence (SIGINT), and Cryptographic Key Management. At Leidos, we offer competitive benefits, including Paid Time Off, 11 paid Holidays, 401K with a 6% company match and immediate vesting, Flexible Schedules, Discounted Stock Purchase Plans, Technical Upskilling, Education and Training Support, Parental Paid Leave, and much more. Join us and make a difference in National Security!

Job Summary A Senior ISSE/Penetration Tester (ISSE/PT) is needed to provide support for adding new capabilities to a complex system with exacting interface, performance and security requirements. The selected individual will become part of a team of Security Engineers working on solving challenging issues on a large, significant program. The position requires a solid understanding of security practices and policies as well as hands‑on vulnerability testing experience. The selected individual will collaborate with other engineers and technical experts in providing improvements to our operational, test, integration, and development systems. The ISSE/PT will develop and lead Security Testing Events by conducting penetration testing, publishing results, and researching penetration testing tools to enhance our overall testing capabilities.

Primary Responsibilities

• Validating and verifying system security requirements and establishing system security designs for large-scale systems, major system elements, and interfacing systems that are part of a large complex network environment with geographically distributed components.
• Identifying and implementing appropriate information security architectures and functionality to ensure uniform application of security policy and enterprise solutions.
• Recommending and developing technical solutions, products, and standards based on current and desired system security architecture.
• Assessing and mitigating system security threats and risks throughout the program life cycle.
• Leading and/or contributing to the security planning, assessment, risk analysis, risk management, certification, and awareness activities for various system and networking operations.
• Collaborating with multiple internal technical experts and communicating with Program Managers and customer POCs when necessary regarding security issues of significant importance.
• Working closely with System Engineering, Test Engineering, and Integration teams to ensure that hardware and software architectures and implementations meet security requirements.
• Analyzing and assessing system implementation against multiple security compliance policies and recommending and implementing enhancements.
• Evaluating security solutions to ensure they meet customer specified requirements for processing information.
• Evaluating the impact of new development on the operational security posture of the system.
• Evaluating, reviewing, and testing critical software.
• Proposing, assessing, coordinating, implementing, and enforcing information systems security policies, standards, and methodologies.
• Auditing and assessing system security configuration settings using common methodologies and tools.
• Managing and enforcing security strategies and policies that affect various components of geographically distributed systems.
• Participating in Program Increment Planning and related agile team activities.
• Providing configuration management for security‑relevant information system software.
• Serving as a subject matter expert in security architecture to include providing advice to Program Managers, customer technical experts, and internal program teams.
• Formulating security compliance requirements for new system features.
• Identifying and remediating security issues throughout the system.
• Supporting risk assessment, risk management, security control assessment, continuous monitoring, service design, and other IA program support functions.
• Working with development teams to enrich team‑wide understanding of different types of vulnerabilities, attack vectors and remediation approaches.
• Planning and conducting security verification testing of relevant type 1 devices.
• Performing internal and external pen tests against systems to determine vulnerabilities and develop mitigation strategies.
• Performing web app pen tests.
• Performing vulnerability risk assessments.
• Performing physical pen tests and security engineering analysis and assessing the vulnerabilities/solutions for the pen testing.

Basic Qualifications

• Bachelor’s degree in Computer Science, Information Assurance, Information Security System Engineering, or a related discipline, and at least 12 years of relevant experience.
• Additional experience may be substituted for a degree.
• Must have extensive, demonstrated knowledge of and experience with common security tools, such as Nessus, NMAP and Wireshark hardware/software security implementation, communication protocol, encryption techniques/tools, and web services.
• Must have in‑depth understanding and extensive experience with security practices and policies and hands‑on vulnerability testing using Tenable Nessus scanning products and/or nmap (Network Mapper).
• Must have experience with Defense in Depth Principals/technology, including access control, authorization, identification and authentication, public key infrastructure, network and enterprise security architecture, and applying risk assessment methodology to system development.
• Must have experience applying Risk Management Framework.
• Must have experience formulating and assessing IT security policy.
• Must have experience with secure configurations of commonly used desktop and server operating systems.
• Must have experience with penetration testing tools.
• Must have experience developing and implementing integrated security services management processes, such as assessing and auditing network penetration testing, anti‑virus planning assistance, risk analysis, and incident response.
• Must have experience providing information assurance support for application development that includes system security certifications and project evaluations for firewalls that encompass system development, design, and implementation.
• Must be comfortable working on multiple systems and components simultaneously in various configurations.
• Must be able to effectively plan and prioritize tasking and communicate clearly regarding technical options and trade‑offs.
• Must be capable of performing high quality work both independently and with a team in a fast‑moving environment.
• Must have strong verbal and written communications skills.
• Must be committed to adopting and adhering to best practices.

Preferred Qualifications

• DoD 8570 compliance with IASAE Level 2 or 3.
• Information Systems Security Engineering Professional (ISSEP) Certification and/or Computer Information Systems Security Professional (CISSP) Certification.
• Experience with scripting languages.
• Candidates with certifications in the following areas are strongly preferred:
• GIAC Web Applications Penetration Tester (GWAPT)
• GIAC Penetration Tester (GPEN)
• Certified Ethical Hacker (CEH)
• Certified Information Security Manager (CISM)
• Certified Web Application Defender (GWEB)
• Certified Information System Security Professional (CISSP)

Clearance Required: Must have TS/SCI with Polygraph.

At Leidos, the opportunities are boundless. We challenge our staff with interesting assignments that allow them to thrive professionally and personally. For us, helping you grow your career is good business.

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

Original Posting: April 28, 2026

Pay Range

Pay Range $131,300.00 - $237,350.00 The Leidos pay range for this job level is a general guideline only and 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. Leidos Leidos is an industry and technology leader serving government and commercial customers with smarter, more efficient digital and mission innovations. Headquartered in Reston, Virginia, with 47,000 global employees, Leidos reported annual revenues of approximately $17.2 billion for the fiscal year ended January 2, 2026. For more information, visit

Pay and Benefits Pay and benefits are fundamental to any career decision. That's why we craft compensation packages that reflect the importance of the work we do for our customers. Employment benefits include competitive compensation, Health and Wellness programs, Income Protection, Paid Leave and Retirement. More details are available here.

Securing Your Data Leidos will never ask you to provide payment-related information at any part of the employment application process. And Leidos will communicate with you only through emails that are sent from a Leidos.com email address. If you receive an email purporting to be from Leidos that asks for payment-related information or any other personal information, please report the email to View email address on click.appcast.io.

Commitment and Diversity All qualified applicants will receive consideration for employment without regard to sex, race, ethnicity, age, national origin, citizenship, religion, physical or mental disability, medical condition, genetic information, pregnancy, family structure, marital status, ancestry, domestic partner status, sexual orientation, gender identity or expression, veteran or military status, or any other basis prohibited by law. Leidos will also consider for employment qualified applicants with criminal histories consistent with relevant laws.

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