Senior Unix Systems Administrator Jobs in Wisconsin

ISCorp Job Description

Job Title:
Senior Security Systems Administrator

Department / Reports To:
Cyber Security | Reports to: Patrick Barwick

Job Summary

The Senior Security Systems Administrator leads the administration, optimization, and continuous improvement of ISCorp’s security infrastructure and operational defense platforms across hosted customer environments and internal systems. This role serves as an advanced technical resource for the deployment, configuration, monitoring, hardening, and support of critical security technologies, including SIEM, EDR/XDR, identity controls, email security, vulnerability management, and incident response tooling.

The Senior Security Systems Administrator operates with a high degree of independence and technical judgment, handling complex security events, driving remediation efforts, improving detection and response capabilities, and strengthening the security posture of production environments. This role partners closely with Infrastructure, Network, Engineering, Operations, and Compliance teams, and provides mentorship to less experienced administrators.

Key Responsibilities

• Lead administration and optimization of security platforms, including SIEM, EDR/XDR, vulnerability management, log management, email security, and identity protection systems.
• Investigate and respond to complex security alerts, incidents, and system anomalies, including containment, root cause analysis, recovery coordination, and post-incident improvements.
• Design and refine alerting logic, dashboards, detection rules, and correlation use cases within SIEM and monitoring platforms.
• Lead security hardening efforts across Windows systems, Active Directory, application platforms, and supporting infrastructure.
• Oversee security patching strategy and coordination for servers, endpoints, and infrastructure platforms, especially for critical or high-risk vulnerabilities.
• Serve as an escalation point for advanced endpoint protection, malware, ransomware, identity, and suspicious activity investigations.
• Lead vulnerability management activities, including prioritization, remediation planning, validation, and trend analysis.
• Administer and optimize Microsoft O365 security controls, including Defender, Conditional Access, MFA, Exchange security, and identity governance-related controls.
• Partner with Compliance and leadership teams on audits, risk assessments, evidence collection, control maturity, and remediation planning.
• Develop and maintain security standards, technical procedures, architecture documentation, and incident response playbooks.
• Provide technical leadership on security initiatives, tool improvements, and cross-functional infrastructure projects.
• Mentor Associate and intermediate-level administrators by providing guidance, review, and knowledge transfer.
• Participate in and help coordinate high-severity on-call response and escalation activities.
• Identify automation opportunities that improve visibility, consistency, response time, and operational resilience.

Required Qualifications

• Bachelor’s degree in Computer Science, Information Systems, Cybersecurity, or a related field; or equivalent work experience.
• Minimum of 5–7 years of progressive experience in systems administration, security operations, or infrastructure security roles.
• Strong hands-on experience with enterprise security tools, including SIEM, EDR/XDR, vulnerability management, and identity/access controls.
• Advanced proficiency with Windows Server, Active Directory, Group Policy, and system hardening practices.
• Strong understanding of virtualization, hosting, and production infrastructure technologies, including VMware, Hyper-V, and OpenShift.
• Working knowledge of scripting and automation tools such as PowerShell, Bash, or Ansible.
• Demonstrated ability to handle complex troubleshooting, incident response, documentation, and cross-functional coordination.

Preferred Qualifications

• Experience with Linux administration and hybrid Windows/Linux environments.
• Experience with cloud security in Azure, AWS, or Google Cloud environments.
• Relevant certifications such as Security+, CySA+, CISSP, SC-200, AZ-500, or equivalent.
• Familiarity with firewall administration, backup/security resilience controls, and enterprise security architecture concepts.
• Exposure to ITIL, change management, or formal project leadership practices.

Key Skills & Attributes

• Advanced analytical and problem-solving skills.
• Strong independent judgment and ownership of complex work.
• Ability to lead technical initiatives and influence peers across teams.
• Strong written and verbal communication, including the ability to explain risk and technical issues clearly.
• Commitment to operational excellence, continuous improvement, and mentoring others.

Work Environment & Benefits

ISCorp offers a competitive salary and a full benefits package, including health, dental, 401(k), and profit sharing. Our Mequon headquarters provides a collaborative office environment with minimal travel requirements and an in-house fitness facility available to employees.

About ISCorp

With headquarters in Mequon, Wisconsin, ISCorp serves customers around the world. We deliver secure, private cloud solutions that support critical applications and data processing for a wide range of industries. Our focus is on exceeding customer expectations through technical excellence, innovation, and outstanding service.