Senior Microsoft Systems Administrator

Key Responsibilities

• Install, configure, harden, patch, and maintain Windows Server (2019/2022+) and Windows 10/11 workstations in accordance with NIST SP 800-53 Rev. 5 controls.
• Implement and validate security controls across families including Access Control (AC), Configuration Management (CM), Identification & Authentication (IA), Audit & Accountability (AU), System & Communications Protection (SC), and others relevant to endpoint/server platforms.
• Manage Group Policy Objects (GPOs), security baselines, and Intune/Microsoft Endpoint Manager policies to enforce 800-53-aligned configurations (e.g., password policies, account lockout, least privilege, firewall rules, AppLocker, BitLocker).
• Perform hardening tasks including: Enforcing deny-by-default/allow-by-exception execution policies, Configuring host-based firewalls and intrusion detection/prevention, Implementing multi-factor authentication and privileged account management, Enabling cryptographic protections for data at rest/transit, Removing unnecessary services, features, and default accounts.
• Administer Microsoft tools for compliance: Active Directory, Microsoft Endpoint Configuration Manager (SCCM/MECM), Microsoft Intune, Azure AD/Entra ID, Defender for Endpoint, and Azure Policy (where hybrid/cloud-integrated).

Required Qualifications

• 4+ years of hands-on experience administering Windows servers and workstations in enterprise environments.
• Demonstrated experience implementing NIST SP 800-53 security controls on Microsoft platforms.
• Proficiency with Microsoft administration tools: Active Directory, Group Policy, PowerShell, SCCM/MECM, Intune, Defender suite.
• Understanding of key 800-53 control families as applied to endpoints/servers (AC, AU, CM, IA, SC, SI, etc.).
• Experience with hardening techniques, baseline configuration management, and least-privilege principles.
• Familiarity with compliance tools (Nessus/Tenable or similar).
• Strong scripting skills (PowerShell preferred) for automation and compliance checks.

About Seneca Resources

Seneca Resources is a trusted career partner that provides opportunities for professionals to grow their careers while making an impact. We invest in our employees' success, celebrate their achievements, and connect them to meaningful work with leading organizations nationwide. Seneca Resources is committed to fostering a diverse and inclusive workplace and is an Equal Opportunity Employer.