Senior ML Engineer - Malware Detection (remote work)

CloudLinux Inc.; Madrid; Remote; EUR 134,000 - 170,000; Full time

Benefits offered by this job

Fully remote work worldwide

Education budget

Gym/sports reimbursement

Job summary

CloudLinux, a global remote-first company, is seeking a Senior ML Engineer to turn malware data into production-grade detection. You will develop models to detect web malware, including PHP, JavaScript, and HTML threats, and generate signatures that scale across fleets.

You will work with GPUs, an experimentation track, and direct leadership, collaborating with malware analysts and infrastructure engineers to improve false positives and negatives while shipping robust detection pipelines.

Qualifications

• Senior ML Engineer to turn malware data into detection systems.
• Experience with model deployment and signatures generation.
• Familiar with GPU-based training and ML workflows.

Responsibilities

• Decide which files on a server deserve closer inspection.
• Tell malicious code from benign at fleet scale.
• Generate detection signatures automatically from campaigns.
• Route files to the correct detection engine and reduce FP/FN.
• Prove model improvements before shipping.

Skills

ML engineering

Python

GPU training

Security ML

Tools

GitLab

Jenkins

Redash

Jira

Slite

Job description

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 is CloudLinux's security suite for Linux web servers: real-time and background malware scanning, automated cleanup, a WAF, runtime PHP protection (Proactive Defense), a database malware scanner, and IP reputation. It runs on hosting providers' shared, VPS, and dedicated servers, so new web-malware campaigns land on our fleet early.

We sit on one of the largest labeled corpora of live web-server malware in the industry: files, verdicts, cleanup outcomes, and analyst decisions collected from production hosting servers every day. It already drives our signatures, heuristics, and ML models, and there is far more to get out of it. We are looking for a Senior ML Engineer who will turn that data into detection that ships — classifiers, LLM-assisted triage and generated signatures — and keep exploring new ML/LLM methods against it, measured by the product's false-negative and false-positive rates, not by notebook accuracy.

Our dataset focuses on web malware — PHP, JavaScript, HTML phishing kits, infected WordPress and Joomla plugins and themes, database injections — with the context around each file.

What you'll work with:

• Malware samples from production servers, with verdicts and analyst decisions
• Years of signatures and detection rules
• Customer-reported false negatives and false positives
• Runtime behavior of code on live sites
• Web-attack traffic
• File metadata and how files spread across servers
• Cleanup outcomes, including what came back

What you will do:

The goal is 10x more malware detected at the same or lower false-positive rate. Hand-written rules and faster pipelines will not get there; models trained on our data might.

• Decide which files on a server deserve a closer look, within tight CPU and memory budgets
• Tell malicious code from benign at fleet scale and a sensible cost per file
• Generate detection signatures automatically from new campaigns
• Catch malware that only looks malicious in context, such as phishing pages and script injections
• Route each file to the right detection engine
• Make cleanup precise so sites stay clean afterwards
• Prove each model improves detection before it ships

How we work:

You get an experimentation track, GPUs, and a direct line to leadership; in return, you bring numbers, not opinions.

• Remote-first, async across UTC−5 to UTC+8. Decisions are written down (ADR-Lite) and public by default
• Hardware follows evidence: Each training direction starts with dedicated GPUs on our own bare metal; leadership has committed to fund more when the case is made with data
• Agentic engineering: Claude and Codex are the default tools, wired to GitLab, Jenkins, Redash, Jira, and Slite through MCP servers. We look at how engineers work with agents — context, specificity, review quality — not only at output
• Close to ground truth: You work daily with malware analysts, detection and infrastructure engineers, and the rest of our ML team
• Ship gates: No model or build goes out if it raises false positives or false negatives on our past-error sets. Blameless post-mortems within 24 hours

What you'll deliver:

You own the path from raw samples to a model in production, and the numbers that prove it helped.

• First month: A first model trained on production data and measured against today's engines — suspicious-file triage or a metadata model. The evaluation harness in place: splits by time and campaign so families don't leak, and a regression set from past FPs and FNs
• By month 3: Several models in production: some in shadow mode building evidence, some live and producing real detections, all gated on the past-error regression set. A training setup that keeps its GPUs busy. A written proposal (ADR) for the detection cascade, with cost per file and hardware needs
• By month 12: Models are a main source of new detections, reported as share of new detections and FN-rate trend. Retraining on fresh analyst and FN labels on a fixed cadence. Generated signatures inside the analyst workflow. Two or three parallel training directions that other engineers can run with your tooling

It is a strong plus if you have:

• Web malware, webshells, phishing kits or WordPress security experience
• Models over code: AST or token features, code LLMs, graph models on program structure
• Malware clustering and similarity analysis
• Multi-GPU training on your own bare metal; MLflow or Weights & Biases; dataset versioning
• Go or Rust, for on-server inference
• Published work or talks on ML for security

Benefits:

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

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