Staff Security Engineer, Imunify360 (remote work)

Location: Lisbon, Portugal; Warsaw, Poland; Madrid, Spain; Prague, Czechia 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: cloudlinux.com We are currently hiring a Staff Security Engineer within the Imunify360 product. Imunify360 is CloudLinux's security suite for Linux web servers. It protects hundreds of thousands of hosting servers and the websites running on them, so it sees most large-scale web attacks early — often in the first hours. Check out our website for more information: https://imunify360.com/ Role Mission & Scope At Imunify360, protecting customers from evolving cyber threats requires close collaboration between security research, engineering, and other teams. Responding to complex attack campaigns involves more than identifying threats — it requires understanding attack techniques, developing effective detection and mitigation strategies, and ensuring customers are protected. As a Staff Security Engineer , you'll take end-to-end technical ownership of complex security challenges, from initial threat discovery and analysis to detection, mitigation, and post-incident review. This is a hands-on technical leadership role focused on practical security engineering rather than SOC monitoring, compliance, or purely theoretical research. You'll analyze malware and exploit code, develop detection and mitigation tools, anticipate emerging attack techniques, and ensure security findings translate into production-ready detections, mitigations, and fixes. You'll work closely with engineering, security research, support, external partners, and the broader security community to coordinate responses and drive continuous improvements in our security capabilities. As an individual contributor , you won't have direct reports or people management responsibilities. All security research and testing are conducted within authorized boundaries, with clearly defined scope and responsible disclosure practices. Your mission is to strengthen Imunify360's ability to detect, prevent, and respond to emerging threats, delivering measurable security improvements that protect customers at scale. What you will own Malware and campaign mitigation Lead response to large-scale exploitation and malware campaigns: triage, root cause, and mitigation across every protection layer of the product. Reverse-engineer malware and exploits targeting Linux servers and web applications. Track campaigns over time, not just individual samples: cluster indicators, connect activity to known actors and toolkits, anticipate the next variant. Define and run measurable outcomes per campaign: time to detect, time to protect, cleanup effectiveness, reinfection rate. Security response coordination Own the security incident and response process, both for threats against our customers and for vulnerabilities in our own product: severity model, runbooks, communication, escalation. Coordinate with external parties — software vendors, partners, CERTs/CSIRTs, abuse desks, other security vendors. Drive responsible disclosure where we find vulnerabilities. Be the technical voice in security advisories and partner briefings, together with Product and Support. Triage external vulnerability reports. Offensive security on our own product Red-team our product and infrastructure. Assume a capable attacker who already has a foothold. Threat-model new features before they ship; own the security review gate for high-risk changes. Turn findings into fixes with the owning teams, not just reports. Detection engineering and tooling Raise the quality bar of detections: false-positive budgets, test corpora, staged rollout with measurement gates and fast rollback. Build and automate the analysis pipeline: dynamic analysis, honeypots, telemetry-driven hunting, ML-assisted triage where it measurably helps. Write production code for these tools; expect 30–50% of your time to be hands-on building. Turn telemetry into intelligence: emerging exploits, attacker infrastructure, trends — shared as internal briefs and selected public research. People multiplier (no direct reports) Mentor analysts and engineers; raise the security skill level across teams. Bar-raiser in security hiring loops. Key Milestones 30 days: Analyzed real threats end-to-end. Mapped the current response flow and where it breaks. Shipped at least one detection or mitigation to production. 90 days: Security response process and severity model published and agreed. Led at least one real campaign response with a written post-mortem. Baseline response metrics in place. 6 months: Time from first sighting to protection measurably reduced vs. baseline. First red-team review completed, top findings fixed. Working relationships with key external partners. 12 months: Recognized internally and externally as the owner of security response. Public research or disclosures published. Teams can run a standard campaign response without you. Requirements Must have 10+ years in security engineering, malware research, incident response, or offensive security, with several years leading cross-team work at Staff/Principal/Lead scope. Deep hands-on malware analysis and reverse engineering skills. Strong web application security and practical exploitation experience. Deep Linux knowledge from both the attacker's and the defender's side. Proven incident response leadership on large-scale events: you have run the response, written the advisory, and closed the post-mortem. Production coding in Python plus a systems language (Go, Rust or C). Experience with coordinated vulnerability disclosure and working with the security community. Clear, short writing for both engineers and non-technical stakeholders; works well async across time zones. Daily user of AI tools for analysis and coding, with critical judgment about their output. Nice to have Background in hosting or large web ecosystems. Detection authoring at scale (signatures, WAF/IDS rules). Kernel-level monitoring and rootkit detection. Threat intelligence practice and actor tracking. ML for malware classification. Public track record: CVEs, published research, talks, CTFs, open-source security tools. Relevant certifications are a plus, not a requirement. Benefits What's in it for you? Stay hands-on technically while owning complex, high-impact engineering work. Work on challenging Linux, automation, and cybersecurity problems across mature and newer products. Influence technical direction and make meaningful architectural decisions. Work independently with a high level of ownership and autonomy. Fully remote work with flexible working hours. 24 paid vacation days, 10 national holidays, and unlimited sick leave. Private medical insurance compensation. Co-working and gym/sports reimbursement. Education budget. Opportunity to receive a reward for innovative ideas that the company can patent. 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