As a Security Engineer at Open Systems, you will play a critical role in safeguarding global enterprise environments. Open Systems is a pioneer in secure cloud enablement, delivering cutting-edge Secure Access Service Edge (SASE) and Managed Detection and Response (MDR) solutions. In this position, you are not just maintaining security protocols; you are designing, implementing, and optimizing the very systems that protect multinational corporations from sophisticated cyber threats.

Your work will directly impact the resilience and reliability of core network and security infrastructures. Whether you are focusing on web security, secure software systems engineering, or security operations, you will be tasked with building highly scalable, secure, and robust systems. This requires a deep understanding of how security integrates with modern network architectures, cloud environments, and software delivery pipelines.

The engineering culture at Open Systems is characterized by high technical standards, professional engagement, and a collaborative, team-focused environment. Joining this team means working alongside world-class experts in Switzerland and globally, solving complex, real-world security challenges at scale. It is an environment that will both challenge your technical limits and support your professional growth.

The interview process at Open Systems is highly technical and comprehensive. The questions below are drawn from real candidate experiences and are designed to assess your foundational knowledge, practical problem-solving capabilities, and architectural thinking. Use these questions to identify patterns in what the hiring team prioritizes rather than simply memorizing answers.

Foundational Systems & Networking

• Explain the step-by-step process of a TCP three-way handshake and how stateful firewalls track these states.
• How do you troubleshoot a server that is experiencing intermittent network packet loss using native Linux tools?
• Describe the differences between symmetric and asymmetric encryption and how both are utilized in a standard TLS handshake.

Preparing for an interview at Open Systems requires a structured approach to showcasing your technical depth and collaborative mindset. The hiring team looks for well-rounded engineers who can translate theoretical security concepts into practical, production-grade solutions.

Technical Fundamentals – You must demonstrate a flawless command of networking protocols, operating system internals (especially Linux), and core security concepts. Interviewers will push you to explain the "why" behind technologies, testing the depth of your knowledge rather than your ability to recall buzzwords.

Structured Problem-Solving – When presented with complex security scenarios, your ability to break down the problem methodically is critical. Walk your interviewer through your diagnostic process, state your assumptions clearly, and evaluate the trade-offs of your proposed solutions.

Communication & Presentation – Security engineering is highly collaborative. You must be able to explain complex technical risks and architectural decisions in a clear, concise manner. This is especially vital during the presentation stage of the interview process.

Cultural Alignment – Open Systems values professional engagement, intellectual curiosity, and a strong team focus. Show that you are receptive to feedback, eager to learn from others, and passionate about building secure systems that enable business success.

The interview process at Open Systems is rigorous, transparent, and highly structured. It is designed to evaluate your technical capabilities, presentation skills, and cultural alignment over three distinct stages. Candidates frequently note that the process is highly professional, challenging, and respectful of their time.

The process typically unfolds as follows:

• Initial Screening & Knowledge Check – A short, focused call with the team lead or a senior engineer. This round serves as a technical baseline, covering foundational cybersecurity, networking, and Linux administration concepts.
• Technical Presentation – A deeper dive where you present on a security or engineering topic of your choice. This stage evaluates your technical depth, communication skills, and ability to defend your engineering decisions under questioning.
• Team Meeting & Closing – A final round where you meet the broader engineering team. This stage focuses on cultural fit, collaborative dynamics, and alignment with the team's working style, followed by a closing conversation about the role and next steps.

The timeline above outlines the standard progression from your initial contact to the final decision. While the exact duration can vary based on candidate availability and location, Open Systems maintains an efficient pace to ensure a smooth candidate experience. Use this structure to organize your preparation, focusing first on core technical concepts before refining your presentation materials.

To succeed at Open Systems, you must perform strongly across several core evaluation areas. The interviewers will assess your theoretical understanding and practical execution in each of these domains.

Foundational Systems & Networking

A massive portion of the Open Systems infrastructure relies on secure, high-performance networking and robust systems administration. You must demonstrate a deep familiarity with how data moves across networks and how operating systems manage resources.

Be ready to go over:

• Network Protocols – Deep understanding of TCP/IP, UDP, DNS, DHCP, routing protocols, and the OSI model.
• Linux Administration – Command-line proficiency, system configuration, process management, and network troubleshooting tools.
• Network Security – Firewalls, intrusion detection/prevention systems (IDS/IPS), VPN technologies, and secure routing.
• Advanced concepts – BGP routing security, network namespaces, kernel-level packet filtering (e.g., eBPF, iptables), and advanced TLS configurations.

Example questions or scenarios:

• "How would you identify and mitigate a DNS amplification DDoS attack at the network edge?"
• "A Linux server is unable to resolve external hostnames. Walk me through your diagnostic steps to isolate the issue."
• "Explain how MTU path discovery works and how ICMP blocking can impact network performance."

Incident Response & Scenario Analysis

As a Security Engineer, you must be prepared to handle real-world security incidents. Interviewers will present you with complex, ambiguous scenarios to evaluate your analytical thinking, risk assessment, and containment strategies.

Be ready to go over:

• Triage & Analysis – How to read and correlate logs from diverse sources, including firewalls, endpoints, and web servers.
• Containment & Mitigation – Strategies for isolating compromised hosts, blocking malicious traffic, and preserving evidence.
• Post-Incident Review – Conducting root-cause analysis and implementing long-term preventative controls.
• Advanced concepts – Analyzing advanced persistent threat (APT) lateral movement, parsing memory dumps, and decoding obfuscated malicious scripts.

Example questions or scenarios:

• "You detect anomalous outbound traffic on port 443 from an internal database server. What are your immediate steps to investigate and contain this?"
• "How would you handle a situation where a high-privilege administrative account is suspected of being compromised?"
• "Describe how you would construct a detection rule to identify lateral movement using compromised credentials."

Web Security & Software Systems Engineering

For roles focused on web security and software systems, you must demonstrate a strong security-first mindset when designing and reviewing application architectures.

Be ready to go over:

• OWASP Top 10 – Detailed knowledge of common web vulnerabilities (e.g., Injection, Broken Authentication, SSRF) and their remediations.
• Secure Architecture – Designing secure APIs, managing identity and access (IAM), and implementing defense-in-depth patterns.
• Cryptography – Proper implementation of encryption, hashing, key management, and secure communication protocols.
• Advanced concepts – Content Security Policy (CSP) bypasses, OAuth 2.0 grant flow security, and securing microservices in containerized environments.

Example questions or scenarios:

• "How would you secure a microservices-based application where services need to authenticate with each other securely?"
• "Explain the mechanics of a Server-Side Request Forgery (SSRF) attack and how to prevent it at both the network and application layers."
• "What security considerations must be addressed when migrating a legacy monolithic web application to a containerized cloud environment?"

The day-to-day responsibilities of a Security Engineer at Open Systems are dynamic and highly impactful, blending engineering rigor with operational vigilance.

• System Design & Implementation – You will design, build, and maintain secure, scalable software systems and network architectures that form the backbone of the company's SASE and security service offerings.
• Security Monitoring & Incident Handling – You will analyze security alerts, investigate potential threats, and execute rapid containment and remediation strategies to protect both internal systems and client environments.
• Continuous Security Posture Improvement – You will conduct regular security assessments, vulnerability scans, and architectural reviews to proactively identify and remediate weaknesses before they can be exploited.
• Tooling & Automation – You will develop custom scripts, tools, and automated workflows to streamline security operations, improve detection capabilities, and enhance overall engineering efficiency.
• Cross-Functional Collaboration – You will work closely with product management, network engineering, and customer success teams to ensure security is seamlessly integrated into every product and service delivered by Open Systems.