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CoolSys

Refrigeration and HVAC design, installation, maintenance

IT Security Engineer

Security Engineering & ArchitectureConfirmed live in the last 24 hours
Full-timeUnited StatesIn-person

About the Job

Requirements

  • Hands-on experience delivering improvements in cybersecurity, infrastructure, networking, cloud operations, identity, DevOps, or systems engineering.
  • Working knowledge across identity, networking, cloud, endpoint, and application security, with deeper practical capability in at least two areas.
  • Ability to explain technical work as a coherent sequence: initial condition, evidence collected, diagnosis, change made, validation method, result, and lessons learned.
  • Experience distinguishing personal contributions from broader team responsibilities.
  • Ability to support technical claims with consistent details about architecture, protocols, dependencies, scale, failure modes, constraints, and testing methods.
  • Experience using appropriate measures such as remediation time, vulnerability age, control coverage, deployment success rate, alert fidelity, authentication failure rate, automation time saved, or reduction in privileged access.
  • Sound judgment when handling credentials, tokens, certificates, private keys, service accounts, and production changes.
  • Clear written and verbal communication with technical and nontechnical stakeholders.

Responsibilities

  • Implement and maintain approved security controls for Microsoft cloud services, enterprise identity, networks, endpoints, servers, applications, and software-delivery processes.
  • Deliver assigned technical work through requirements analysis, implementation, testing, deployment, documentation, and operational handoff.
  • Independently investigate production security issues within areas of proficiency and collaborate with senior engineers, platform owners, or vendors when issues cross unfamiliar architectural boundaries.
  • Automate repeatable security operations using PowerShell, Python, REST APIs, JSON, configuration management, or infrastructure automation.
  • Integrate security platforms with Azure services, GitHub, CI/CD pipelines, identity systems, logging platforms, ticketing workflows, and notification services.
  • Assess control effectiveness, recommend remediation, and validate that approved changes reduce risk without introducing unacceptable operational impact.
  • Support incident investigations using identity activity, network flows, endpoint telemetry, application logs, cloud events, and configuration evidence.
  • Produce implementation records, architecture diagrams, troubleshooting guides, test plans, rollback procedures, and operational runbooks.
  • Implement GitHub repository and workflow protections, including branch controls, pull-request reviews, secrets management, deployment approvals, least-privilege permissions, and automated security testing.
  • Integrate static, dependency, secret, infrastructure-as-code, or configuration scanning into CI/CD pipelines. Implement approved deployment gates, tune noisy findings, document exceptions, and track remediation with application and DevOps teams.
  • Configure and troubleshoot Microsoft Entra ID capabilities, including Conditional Access, multifactor authentication, enterprise applications, application registrations, service principals, managed identities, workload identities, role-based access control, consent, and privileged access.
  • Investigate OAuth 2.0 and OpenID Connect failures using tokens, claims, scopes, permissions, redirect URIs, credentials, sign-in logs, and access policies.
  • Support Active Directory Domain Services, including organizational units, Group Policy, domain controllers, DNS dependencies, Kerberos, SPNs, delegation, LDAP/LDAPS, service accounts, gMSAs, and hybrid identity.
  • Support reviews of Active Directory Certificate Services and PKI configurations, including certificate templates, enrollment permissions, trust chains, certificate authentication, renewal, revocation, private-key protection, and potentially unsafe issuance paths.
  • Trace representative application flows across common network and security boundaries, including IPv4 subnets, VLANs, routes, stateful firewalls, SNAT, DNAT, proxies, load balancers, VPNs, DNS, and RADIUS-controlled access.
  • Use packet captures, flow records, logs, route analysis, and configuration reviews to distinguish network, firewall, proxy, TLS, authentication, and application failures.
  • Implement and validate defined improvements to vulnerability remediation, hardening, least privilege, endpoint protection, cloud configuration, logging, monitoring, and detection coverage.
  • Participate in threat modeling and secure architecture reviews for new systems, APIs, integrations, and infrastructure changes.
  • Deliver planned security improvements while responding to production issues, prioritizing work with the manager when urgent support affects delivery.
  • Implement assigned changes within established designs, seeking review before making architectural changes or accepting significant risk.
  • Test changes, follow change-control procedures, prepare rollback steps, and verify that controls work after deployment.
  • Trace and resolve issues across identity, network, cloud, endpoint, and application boundaries, involving platform owners or senior engineers when needed.
  • Partner with application, networking, cloud, and support teams to address dependencies and make solutions maintainable.
  • Document configurations, decisions, test results, and handoff procedures so others can operate and troubleshoot the solution.
  • Report progress, blockers, trade-offs, and residual risks, using observable results or credible measures to show whether the work achieved its objective.
  • Participate in a reasonable on-call rotation and occasional after-hours maintenance, coordinating changes carefully, communicating service impact, following escalation procedures, and maintaining accurate records of actions and outcomes.

Desired Qualifications

  • Deeper experience in one or more areas such as Microsoft Entra ID, OAuth/OIDC, Active Directory, Kerberos, AD CS, network traffic analysis, GitHub security, CI/CD integration, Azure workload identities, PowerShell, Python, or REST APIs.
  • Familiarity with the NIST Cybersecurity Framework, NIST SP 800-53, CIS Controls, CIS Benchmarks, Microsoft security baselines, or comparable guidance.
  • Microsoft Azure or security certifications, CompTIA Security+, GIAC certifications, or equivalent demonstrated experience.

About the Company

CoolSys

Refrigeration and HVAC design, installation, maintenance

CoolSys provides refrigeration and HVAC services to retail, commercial, and industrial clients. It designs, installs, and remodels systems, converts refrigerants, performs preventative maintenance, repairs, and optimizes energy use and overall system performance. Their products are not a physical device but a service offering: engineers create system designs, technicians install and service equipment, and ongoing monitoring and maintenance help keep temperatures stable and energy use efficient. What sets CoolSys apart is its broad, industry-focused experience across grocery, food service, telecommunication, manufacturing, education, entertainment, and pharma sectors, plus a persistent emphasis on reliability, integrity, and meeting client commitments while addressing environmental sustainability. The company aims to improve clients’ operations, experiences, and work environments through high-quality, dependable service and energy-efficient, properly maintained systems.

Company size
1,001-5,000
Company stage
Debt Financing
Total funding
$150M
Headquarters
Brea, CA
Founded
2017

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