Defender Administrator

Description:

Queen Square Recruitment is seeking an experienced Defender Administrator on behalf of a leading global organisation. This is a contract role based in either Gloucester or Warrington, with a hybrid working model. The successful candidate will play a key role in a large-scale migration project, transitioning legacy antivirus solutions such as Symantec and McAfee to Microsoft Defender (ATP) across both Windows and Linux servers. The position offers a rate of £450 per day (Inside IR35) and will initially run for 6+ months, starting on 30th September 2025.

The Defender Administrator will be responsible for ensuring a smooth and secure migration process within a highly complex, security-sensitive environment. The role requires deep technical expertise in Microsoft Defender technologies, hands-on migration skills, and the ability to document and implement policies that align with industry best practices.

Key Responsibilities:

• Lead the migration of Windows and Linux servers from Symantec/McAfee to Microsoft Defender (ATP).

• Validate and manage AV exclusion policies across the IT estate.

• Implement Microsoft Defender policies, configure AAD device groups for policy deployment, and manage exclusions.

• Develop a structured migration approach tailored to high-security environments.

• Perform network connectivity testing to ensure system readiness.

• Create, configure, and distribute Defender installation files.

• Collaborate with the Image Management team to provide MDE images for auto-scaling environments.

• Deliver full documentation of deployment approaches, policies, and operational processes.

• Provide end-to-end support for Defender deployment, maintenance, and troubleshooting.

• Maintain high levels of endpoint security controls following best practices.

Key Skills & Experience:

• Hands-on expertise in onboarding Microsoft and Linux servers to Microsoft Defender.

• Demonstrated success in leading complex AV migration projects.

• Proficiency in AV exclusion management.

• Strong technical knowledge of Microsoft security technologies, including:

  • Microsoft Defender for Server

  • Microsoft Defender for O365

  • Microsoft Defender for Identity

  • Microsoft 365 Defender

  • Microsoft Cloud App Security

• Experience with Symantec Endpoint Protection Manager (SEPM), McAfee, and Windows Defender configurations.

• Solid understanding of Windows Client (7/8/10) and Server OS (2008/2012/2016) plus Linux (RHEL).

• Skilled in deploying ATP packages via GPO, SCCM, or Intune.

• Strong background in threat analysis, hunting, remediation, and endpoint detection and response.

• Experience creating policies, exclusions, dashboards, and monitoring reports.

• Excellent documentation and communication skills.

Requirements:

• At least 4 years of professional experience in IT security and antivirus/endpoint migration.

• Certified Security Clearance (or eligibility, requiring 5 years’ continuous UK residency).

• Flexibility to work shifts, out-of-hours, and on-call as per rota requirements.