Senior Security Operations Analyst - Microsoft Sentinel and Defender

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The opportunity EY is seeking a senior, hands-on security operations analyst to support Managed Detection and Response services in a multi-customer Managed Security Service Provider environment.
You will lead complex security incident investigations using Microsoft Sentinel and Microsoft Defender XDR, perform threat hunting and detection tuning, and improve response workflows through Microsoft Sentinel automation rules, playbooks, and Azure Logic Apps. You will work across multiple customer environments, provide technical guidance to other analysts, and communicate clear findings and response recommendations to clients.
The successful candidate will bring strong investigative judgement, advanced Microsoft security platform experience, and the ability to manage concurrent incidents and priorities in a client-facing environment.
This job posting relates to an existing vacancy within our organization.
Your key responsibilities:
As a senior technical member of the security operations team, you will:
Security incident investigation and response   Lead the triage and investigation of complex or high-severity security incidents across multiple customer environments.
Correlate endpoint, identity, email, cloud, network, and threat intelligence evidence to determine incident scope, root cause, and business impact.
Develop investigation timelines, document evidence, identify attacker activity, and recommend containment and remediation actions.
Coordinate escalations and response activities with clients, internal teams, and other technical specialists.
Produce clear incident records, client communications, and post-incident findings.
Microsoft Sentinel and Defender operations   Use Microsoft Sentinel and Microsoft Defender XDR to investigate, prioritize, and respond to security alerts and incidents.
Investigate activity across Microsoft Defender for Endpoint, Defender for Identity, Defender for Office 365, Defender for Cloud Apps, and Defender for Cloud.
Write and optimize Kusto Query Language queries for incident investigation, threat hunting, reporting, and detection validation.
Review and tune analytics rules, hunting queries, workbooks, watchlists, parsers, and related detection content.
Identify gaps in telemetry, detection coverage, and platform configuration, then recommend practical improvements.
Automation and continuous improvement   Design, build, test, and maintain Microsoft Sentinel automation rules and playbooks using Azure Logic Apps.
Automate incident enrichment, triage, notification, ticketing, evidence collection, and approved containment actions.
Troubleshoot playbook failures, integration issues, permissions, API connections, and workflow reliability.
Improve analyst workflows and standard operating procedures based on incident lessons, recurring alert patterns, and service metrics.
Apply appropriate approvals, access controls, logging, and error handling to automated response actions.
MSSP service delivery   Manage investigations and technical priorities across multiple customers with different environments, procedures, and service commitments.
Follow customer-specific rules of engagement, escalation paths, response procedures, and service-level requirements.
Work directly with client security and technology teams to gather context, explain findings, and recommend next steps.
Support onboarding and operational improvement of customer environments, including data connectors, telemetry validation, and incident workflows.
Provide technical coaching and peer review to other…