Senior Penetration Testing, Software Assurance & Vulnerability Assessment Engineer

Job Description

Job Description

We are an employee-centric company that truly values our team members and the contributions they make to our customers and the missions they support. We pride ourselves on being forward-leaning thinkers and on building teams that are, and continue to be, technically proficient across a broad range of cyber mission areas. OneZero full-time employees receive a highly competitive benefits package, including health, dental, vision, and life insurance, a 401(k) with company matching, paid time off and holidays, an employee referral program, and educational assistance. Additional details are available on our website:

Position Title: Senior Penetration Testing, Software Assurance & Vulnerability Assessment Engineer

Location : On-site in a SCIF in the National Capital Region (NCR) – Nebraska Avenue Complex, Washington, DC (work locations transitioning to ICCB Bethesda / St. Elizabeths). Telework is not authorized; a designated Key Person must be available on-site during core hours

Clearance: TS/SCI

Job Summary:

Performs advanced penetration testing, vulnerability assessments, and software assurance activities to identify and mitigate security weaknesses across DHS systems.

Education and Experience:

• Bachelor's degree in Cybersecurity, Computer Science, or related field or equivalent years of experience.

• CEH, OSCP, GPEN, CISSP, or equivalent experience

• 15+ years of total cybersecurity experience, with demonstrated SME-level depth across the following disciplines:

• 5+ years conducting penetration testing across multiple domains (network, application, red team, physical, and/or wireless)

• 5+ years in software assurance, including secure code review, threat modeling, SAST/DAST tooling, and vulnerability analysis across multiple languages and platforms

• 4+ years in enterprise patch management and vulnerability remediation, including prioritization frameworks (CVSS, EPSS), SLA enforcement, and remediation validation

• 4+ years architecting, assessing, and securing cloud environments (AWS, Azure, GCP) and/or Cross Domain Solutions (CDS), including cloud-native attack surface analysis

• Significant experience supporting DHS, Intelligence Community (IC), or other federal agency programs, with deep familiarity with RMF, ICD 503, NIST 800-53/800-115, and related compliance frameworks

• Experience briefing findings and recommendations to senior leadership, program managers, and authorizing officials

Essential Duties:

• Conduct advanced penetration testing and vulnerability assessments across networks, applications, AI systems, cloud environments, and DevSecOps pipelines
• Employ both automated tooling and sophisticated manual techniques to identify, validate, exploit, and analyze security weaknesses across complex, multi-domain environments

• Perform red team operations and adversary emulation exercises aligned to MITRE ATT&CK TTPs, simulating realistic threat actor behavior against classified and unclassified systems

• Conduct secure code reviews, static and dynamic application security testing (SAST/DAST), and software assurance activities across multiple languages and platforms

• Assess Cross Domain Solutions (CDS), cloud-native architectures, and hybrid environments for misconfigurations, privilege escalation paths, and lateral movement opportunities

• Analyze and correlate findings across assessments to identify systemic vulnerabilities and patterns, not just individual weaknesses

• Lead and direct penetration test programs across multiple concurrent systems, coordinating scope, scheduling, and resource allocation

• Develop, maintain, and continuously improve penetration testing methodologies, playbooks, and Standard Operating Procedures (SOPs)

• Serve as a subject matter expert and technical authority on offensive security techniques, vulnerability research, and exploit development

OneZero Solutions, LLC is an Equal Opportunity employer. All qualified applicants will receive consideration for employment without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, age, pregnancy, genetic information, disability, status as a protected veteran, or any other protected category under applicable federal, state, and local laws.

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