Sr. Cybersecurity Engineer (ISSE / Product Security Engineering)

Istari Digital; Île-de-France; On-site; EUR 90,000 - 130,000; Full time

Job summary

You will work across secure environments, embedding security into engineering, performing patching, vulnerability scans, and POA&M tracking, with exposure to SIPR, JWICS, and SAP environments.

Qualifications

• Active TS clearance with SCI eligibility required.
• DoD 8570/8140 certification (Security+ min; CISSP/CASP+/CISM preferred) and 5+ years in cybersecurity with hands-on implementation.
• Direct experience with NIST 800-53/800-171 and DISA STIGs.
• ACAS/Nessus experience.
• Background in Systems Administration, Network Engineering, or SOC with security transition.
• Experience in Classified environments (SIPR, JWICS, SAP).

Responsibilities

• Implement NIST 800-53/800-171 security controls directly into system design and platform architecture.
• Lead system hardening and secure configuration across platform components.
• Embed security into the engineering workflow (DevSecOps).
• Perform system patching and STIG implementation and validation.
• Vulnerability scanning (ACAS/Nessus).
• POA&M management and remediation tracking.
• Secure APIs, services, and data pipelines; enforce least privilege, identity, and access controls.
• Support deployment into SIPR/JWICS/SAP environments.
• Identify and remediate security gaps before they reach customer environments.

Skills

Active TS clearance with SCI eligible

Hands-on cybersecurity implementation

DevSecOps integration

NIST 800-53/800-171

Education

DoD 8570/8140 certification (Security+ min; CISSP/CASP+/CISM preferred)

5+ years cybersecurity experience

Tools

ACAS

Nessus

Job description

Security Clearance: Active TS required with SCI eligibility (Poly preferred)

Istari Digital delivers a model-based digital engineering platform that enables defense and aerospace teams to design, integrate, and operate complex systems. Our platform operates in classified, mission-critical environments, where cybersecurity must be engineered into the system—not bolted on.

Role Overview

We are hiring an Information System Security Engineer (ISSE) to serve as the technical implementer of cybersecurity within our platform. This is not a policy or compliance role. You will take security requirements (RMF, NIST, customer constraints) and directly apply them to system architecture, infrastructure, and the software development lifecycle.

What You’ll Do

• Implement NIST 800-53 / 800-171 security controls directly into system design and platform architecture Lead system hardening and secure configuration across platform components Embed security into the engineering workflow (DevSecOps)
• Perform:System Patching STIG implementation and validation Vulnerability scanning (ACAS/Nessus)
• POA&M management and remediation tracking
• Partner with engineering teams to: Secure APIs, services, and data pipelines Enforce least privilege, identity, and access controls Support deployment into: SIPR / JWICS / SAP environments
• Identify and remediate security gaps before they reach customer environments

Required Qualifications

• Active TS clearance with SCI eligibility
• DoD 8570/8140 certification (Security+ minimum; CISSP/CASP+/CISM preferred) 5+ years in cybersecurity with hands-on implementation experience
• Direct experience with:NIST 800-53 / 800-171DISA STIGs
• ACAS/Nessus
• Background in:Systems Administration, Network Engineering, or SOC → transitioned into security Experience working in:Classified environments (SIPR, JWICS, SAP)

What Makes You a Strong Fit

• You’ve actually hardened systems—not documented controls
• You can move between:Low‑level system configuration High‑level security architecture decisions You are comfortable doing manual, in‑the‑weeds work when needed to hit deadlines Track record of stability (2+ years per role preferred)
• Comfortable in a startup environment
• Willing to own problems end‑to‑end, not just your lane

We may use artificial intelligence (AI) tools to support parts of the hiring process, such as reviewing applications, analyzing resumes, or assessing responses. These tools assist our recruitment team but do not replace human judgment. Final hiring decisions are ultimately made by humans. If you would like more information about how your data is processed, please contact us.

• (may be additionally eligible for stipend, one time incentive, or % differential for clearance)