Senior SIEM Engineer

Claranet limited; Porto; On-site; EUR 60,000 - 90,000; Full time

Job summary

Claranet limited in Porto is seeking a Senior SIEM Engineer to join our internal team. You will design and maintain security monitoring solutions across enterprise environments, focusing on Microsoft Sentinel and Graylog.

Responsibilities include developing detection use cases, onboarding log sources, and automating security operations using multiple scripting languages. You will collaborate with infrastructure and security teams to enhance monitoring capabilities and document procedures.

Qualifications

• Proven experience administering and engineering Microsoft Sentinel environments.
• Strong experience writing and optimizing KQL queries for detection engineering.
• Hands-on knowledge of SIEM technologies such as Microsoft Sentinel and Graylog.
• Experience deploying and maintaining Linux-based security infrastructure.
• Familiarity with Docker, Podman, and containerized deployments.

Responsibilities

• Design, implement, and maintain security monitoring solutions across enterprise environments.
• Develop, tune, and optimize detection use cases within Microsoft Sentinel and other SIEM platforms.
• Engineer and onboard log sources, ensuring data quality, normalization, and operational reliability.
• Create, maintain, and improve KQL detection rules, analytics, watchlists, and threat hunting queries.
• Automate security operations using PowerShell, Bash, Python, Ansible, and other scripting technologies.
• Deploy and manage SIEM infrastructure components, including Graylog, Logstash, Syslog-ng, Docker/Podman, and related services.
• Perform security engineering activities to enhance monitoring coverage and detection capabilities.
• Investigate and improve security telemetry, reducing false positives while increasing detection accuracy.
• Collaborate with infrastructure, networking, and security teams to integrate new technologies into the monitoring ecosystem.
• Develop technical documentation, implementation guides, and operational procedures.
• Support vulnerability management initiatives by improving visibility and security monitoring.
• Ensure security monitoring solutions follow industry best practices and operational standards.

Skills

KQL

Microsoft Sentinel

Scripting

Linux security

Docker/Podman

Log collection

English communication

Tools

Graylog

Job description

We're fast learners, hard workers, natural collaborators... and weMake Modern Happen!

Our ambition is to unlock the potential of our digital world so that organisations everywhere can innovate and thrive securely.

We aim to achieve this goal by bringing together the world’s most talented people and the most powerful technologies, combining them to address our customers' challenges and to build something stronger together.

Right now, we are looking for aSenior SIEM Engineerto integrate our internal team, based inPorto.

Your responsibilities include:

• Design, implement, and maintain security monitoring solutions across enterprise environments.
• Develop, tune, and optimize detection use cases within Microsoft Sentinel and other SIEM platforms.
• Engineer and onboard log sources, ensuring data quality, normalization, and operational reliability.
• Create, maintain, and improve KQL detection rules, analytics, watchlists, and threat hunting queries.
• Automate security operations using PowerShell, Bash, Python, Ansible, and other scripting technologies.
• Deploy and manage SIEM infrastructure components, including Graylog, Logstash, Syslog-ng, Docker/Podman, and related services.
• Perform security engineering activities to enhance monitoring coverage and detection capabilities.
• Investigate and improve security telemetry, reducing false positives while increasing detection accuracy.
• Collaborate with infrastructure, networking, and security teams to integrate new technologies into the monitoring ecosystem.
• Develop technical documentation, implementation guides, and operational procedures.
• Support vulnerability management initiatives by improving visibility and security monitoring.
• Ensure security monitoring solutions follow industry best practices and operational standards.

You musthave:

• Proven experience administering and engineering Microsoft Sentinel environments.
• Strong experience writing and optimizing KQL queries for detection engineering.
• Solid experience with SIEM technologies such as Microsoft Sentinel and Graylog.
• Hands-on knowledge of log collection technologies including Syslog-ng, Logstash, NXLog, Windows Event Forwarding (WEF), and Syslog.
• Experience deploying and maintaining Linux-based security infrastructure.
• Strong scripting and automation skills using PowerShell, Bash, Python, or Ansible.
• Familiarity with Docker, Podman, and containerized deployments.
• Proficiency in English to communicate effectively with technical and executive stakeholders.

Wevalue:

• Microsoft certifications such as SC-200 (Microsoft Security Operations Analyst) or AZ-500 (Azure Security Engineer).
• Knowledge of threat modeling frameworks and detection methodologies like MITRE ATT&CK.
• Strong analytical thinking for telemetry optimization and noise reduction.
• Excellent communication skills to convey complex technical concepts to multi-disciplinary teams.
• A proactive approach to continuous learning and adapting to cloud security tools.