Senior System Administrator (Active Directory & Security)

CL Technical Services Ltd.; Sha Tin; On-site; HKD 420,000 - 660,000; Full time

Job summary

CL Technical Services Ltd. seeks a Senior System Administrator (Active Directory & Security) to administer AD DS, maintain reliability, and protect systems across the network.

You will lead vulnerability management, review findings, coordinate remediation, and support Windows Server environments and migrations, audits, and security projects while collaborating with cross-functional teams to improve cybersecurity posture.

Qualifications

• Bachelor's degree in Computer Science, IT, Information Security, or related discipline.
• Minimum 5 years in system analysis, IT infrastructure support, system administration, or security operations.
• Hands-on AD DS administration, maintenance, and troubleshooting.
• Experience with vulnerability management, scanning tools, and remediation coordination.
• Understanding of infrastructure, OS, network, and web app security vulnerabilities.
• Ability to interpret security scan results, assess risk, and distinguish real threats from false positives.
• Familiarity with security governance, compliance, and audit processes; government IT security standards an advantage.
• Experience with Windows Server environments and migrations; strong project management and stakeholder coordination.
• Excellent communication and interpersonal skills for technical and non-technical audiences.

Responsibilities

• Administer, maintain, and support Active Directory Domain Services (AD DS).
• Manage end-to-end vulnerability assessment activities; schedule scans and coordinate remediation.
• Analyze vulnerability reports; identify genuine risks and filter false positives.
• Coordinate and lead infrastructure security initiatives with owners, teams, and vendors.
• Conduct regular security assessments, compliance reviews, and audits per policies.
• Plan and coordinate Windows platform migration projects with minimal service disruption.
• Schedule and track security audits for servers, networks, and applications.
• Gather audit evidence and assist in preparing audit documentation and briefs.
• Collaborate with cross-functional teams to improve cybersecurity posture and efficiency.
• Prepare management reports, technical documentation, audit summaries, and progress updates.

Skills

AD DS administration

Vulnerability management

Security governance

Windows Server

Project management

Stakeholder coordination

Communication skills

Analytical thinking

Education

Bachelor's degree in Computer Science / IT / Information Security

Tools

Vulnerability scanning tools

SAST/DAST tooling

Job description

Senior System Administrator (Active Directory & Security)

Administer, maintain, and support Active Directory Domain Services (AD DS), ensuring system reliability, availability, and security.

Manage end-to-end vulnerability assessment activities, including scheduling scans, operating security scanning tools, reviewing findings, and coordinating remediation efforts.

Analyze vulnerability scan reports and identify genuine security risks while filtering out false positives.

Coordinate and lead infrastructure security initiatives involving system owners, support teams, and external vendors.

Conduct regular system security assessments, compliance reviews, and audits in accordance with established security policies and standards.

Plan and coordinate Windows platform migration projects, ensuring smooth implementation with minimal service disruption.

Schedule and track security audits for servers, networks, and applications, ensuring timely completion by relevant stakeholders.

Gather audit evidence and system information, and assist in preparing audit documentation and assignment briefs.

Collaborate with cross-functional teams to drive continuous improvements in cybersecurity posture and operational efficiency.

Prepare management reports, technical documentation, audit summaries, and project progress updates.

Job Requirements

Bachelor's degree in Computer Science, Information Technology, Information Security, or a related discipline.

Minimum 5 years of experience in system analysis, IT infrastructure support, system administration, or security operations.

Solid hands-on experience in Active Directory Domain Services (AD DS) administration, maintenance, and troubleshooting.

Proven experience in vulnerability management, including the use of vulnerability scanning and application security testing tools (SAST/DAST), as well as remediation coordination.

Strong understanding of infrastructure, operating system, network, and web application security vulnerabilities.

Ability to review and interpret security scan results, assess risk severity, and distinguish genuine threats from false positives.

Familiarity with security governance, compliance requirements, and audit processes.

Knowledge of government IT security standards, policies, and guidelines is an advantage.

Experience with Windows Server environments and migration projects is preferred.

Strong project management and stakeholder coordination skills with the ability to manage multiple initiatives simultaneously.

Excellent communication and interpersonal skills, with the ability to work effectively with technical and non-technical stakeholders.

Strong analytical, organizational, and problem-solving abilities.

Experience preparing professional reports, audit documentation, and management presentations.