Senior Security Engineer - Node.js Proactive Defense

CloudLinux is a global remote-first company. We are driven by our principles: do the right thing, employees first, we are remote first, and we deliver high-volume, low-cost Linux infrastructure and security products that help companies to increase the efficiency of their operations. Every person on our team supports each other and does what we can to ensure we all are successful.

Check out our website for more information https://cloudlinux.com/

Imunify360 Security Suite is a product of CloudLinux Inc., the maker of the #1 OS in security and stability for hosting providers. Imunify is an innovative security solution designed specifically for shared and VPS/Dedicated servers. The automated, easy-to-use solution with the six-layer approach to security delivers comprehensive and complete attack prevention.

What You’ll Work On

You will own the Node.js Proactive Defense initiative — a new runtime security layer for Imunify360 that brings the same in-process protection model we already ship for PHP (PHP auto-immunity / blocking of malicious code at runtime) into the Node.js ecosystem.

Today, hosting providers running multi-tenant Node.js workloads have no equivalent of mod_security + PHP Proactive Defense: malicious code, supply-chain payloads, and post-exploitation behavior execute inside the Node.js process with full privileges of the tenant. Your job is to close that gap.

Concretely, You Will:

• Design and ship a Node.js runtime agent that hooks into the V8/Node lifecycle to trace and block malicious behavior patterns (child_process spawn chains, eval / Function constructors, prototype pollution exploitation, unsafe deserialization, SSRF, path traversal, fs writes to sensitive locations, malicious require() / dynamic import chains, supply-chain poisoning at load time).
• Define the detection model: which behaviors are policy-blockable by default, which are signal-only, and how rules are authored, distributed, and versioned alongside our existing Proactive Defense rule pipeline.
• Integrate the agent with the rest of the on-host Imunify security stack so that Node.js detections, blocks, and incidents flow into the same telemetry pipeline, the same backend event store, and the same admin UI as our other layers (WAF, host-IDS, brute-force protection, malware scanner, patch management). This ships as a first-class layer of Imunify360, not a standalone tool.
• Make it production-safe on shared hosting: low overhead, tenant-isolated, compatible with CageFS / LVE, and resilient to hostile tenants who will try to disable or evade the agent.
• Build the pipeline that turns CVE write-ups and threat-intel feeds into shipped detections. The system — not a human — ingests advisories, extracts the exploit primitive, generates and tests rule candidates against a corpus, and rolls them out with the right signal-only / blocking posture.
• Own the closed feedback loop from production blocks (true positives, false positives, evasions) back into the next generation of rules.

This is a green-field, security-engineering-led role with direct product impact: the detections you write will run on hundreds of thousands of servers.

Must have:

• Security engineer mindset: thinks in attack surfaces, exploit primitives, and defense-in-depth - not just in OWASP checklists. Can read a CVE writeup and reconstruct the primitive, not just the patch.
• Runtime/exploitation knowledge across languages: prototype pollution, deserialization, command injection, SSRF, path traversal, supply-chain poisoning - knows why these primitives exist, not just that they have names.
• Systems-level development: Linux daemons, systemd, privileged processes, IPC, namespaces/cgroups, file-descriptor and signal hygiene.
• Low-level / instrumentation instinct: has hooked, traced, or intercepted something in production - LD_PRELOAD, eBPF, ptrace, JVM agents, Python sys.settrace, language-runtime preload, kernel modules. The specific tech doesn’t matter; the instinct does.

Nice to have:

• Shared-hosting / multi-tenant Linux experience: LVE, CageFS, control-panel ecosystems, or analogous tenant-isolation work.
• Comfort working from a CVEs and threat-intel feed as primary product input.

What’s in it for you?

• A focus on professional development.
• Interesting and challenging projects.
• Fully remote work with flexible working hours, that allows you to schedule your day and work from any location worldwide.
• Paid 24 days of vacation per year, 10 days of national holidays, and unlimited sick leaves.
• Compensation for private medical insurance.
• Co-working and gym/sports reimbursement.
• Budget for education.
• The opportunity to receive a reward for the most innovative idea that the company can patent.

By applying for this position, you consent to the processing of your personal data as described in our Privacy Policy (https://cloudlinux.com/candidate-privacy-notice), which provides detailed information on how we maintain and handle your data.