Senior Security Engineer - Application Security

Senior Security Engineer — Application Security Location: United States — Remote | Department: Security | Reports to: Chief Information Security Officer Role overview Nasuni is seeking a Senior Security Engineer specializing in application security and penetration testing to protect our growing portfolio of enterprise data infrastructure and SaaS products. You will identify and validate vulnerabilities, conduct penetration tests, guide secure design decisions, and work with Engineering to remediate and retest findings across Nasuni products, Resilio, DryvIQ, cloud services and emerging AI-enabled capabilities. Scope and impact You will independently execute complex security assessments, coordinate assigned testing initiatives, and recommend risk-based priorities within established security standards. This hands-on role combines technical judgment, practical automation, and cross-functional influence. Responsibilities Conduct threat modeling, secure design and targeted code reviews for web applications, APIs, cloud services and appliances. Perform manual and tool-assisted penetration testing; document reproducible findings and verify fixes. Coordinate external penetration-test scoping, execution, report quality review, remediation tracking and retesting. Validate customer-reported vulnerabilities and advise Engineering on prioritization, mitigation and closure. Improve SAST, SCA, secrets detection, container scanning and CI/CD security workflows with engineering partners. Support SBOM and software supply-chain vulnerability impact analysis. Assess AI-enabled product features for access-control weaknesses, prompt injection and unintended data exposure. Use approved AI-assisted tools for test planning, code analysis and research; independently verify outputs and protect confidential data. Share practical security guidance and improve repeatable assessment processes. Must-have qualifications Approximately 5+ years of relevant security engineering experience with substantial hands-on AppSec or penetration testing. Demonstrated manual testing of web applications and APIs, including authentication and authorization issues. Experience with threat modeling, secure code review, vulnerability validation and remediation retesting. Experience coordinating third-party penetration tests and reviewing technical findings. Practical knowledge of OWASP guidance, security testing tools and application security controls in the SDLC. Ability to read code and automate tasks using a relevant programming or scripting language. Working knowledge of cloud services, Linux, containers or Kubernetes; effective technical communication. Preferred qualifications Enterprise SaaS, hybrid-cloud or appliance security experience. SBOM, CycloneDX/SPDX, supply-chain security and CI/CD tooling experience. LLM or agentic feature testing, M&A assessments, or audit evidence preparation. OSCP, GWAPT, GPEN, GWEB, CSSLP or equivalent demonstrated skills. Ideal differentiators Independently discovered complex flaws and verified remediation; improved repeatable security workflows; balanced risk across SaaS and hybrid infrastructure; responsibly applied AI-assisted analysis with demonstrable validation. Experience guidelines Five or more years of relevant experience is typical, with meaningful direct responsibility for application security assessments. Equivalent demonstrated expertise is valued. A related degree or equivalent practical experience is welcome. Success measures 90 days: establish findings, testing environment and remediation visibility. Six months: deliver risk-based internal testing and improve threat-modeling consistency. Twelve months: coordinate the annual external assessment and show measurable remediation progress. About Nasuni Nasuni is the unstructured data foundation for enterprise teams—and the AI that supports them. We manage, protect, and activate the world’s unstructured data so organizations can work smarter, spend wisely, and create safely without limits. As a Vista-backed SaaS data infrastructure company, Nasuni is transforming how enterprises manage file data with a next-generation, AI-ready platform—turning massive file stores into secure, actionable, and AI-ready data for intelligent automation, analytics, and global collaboration. Why work at Nasuni? As part of our commitment to your well-being, we are pleased to offer comprehensive benefits packages to employees across the US. Benefits packages generally include: • Best in class employee onboarding and training • "Take What You Need” paid time off policy • Comprehensive health, dental and vision plans • Company-paid life and disability insurance • 401(k) and Roth IRA retirement plan • Generous employee referral bonuses • Flexible remote work policy • 10 Paid Holidays • Wide array of wellbeing offerings • Pre-tax savings accounts with company contributions • Great team culture and social activities • Collaborative workspaces • Free on-site fitness centers and stocked kitchens in select office locations <span c