Senior Cloud Security Engineer – Azure & SIEM (Contract)

Flagstone; Greater London; On-site; GBP 90,000 - 120,000; Full time

Job summary

Flagstone is seeking a senior security engineer to own and evolve cloud security, detection tooling, and incident response across Azure. You’ll operate Microsoft Sentinel, Defender for Cloud, and contribute to detection-as-code while coordinating pen tests and remediation with multiple engineering squads.

You’ll bring hands-on SIEM experience, Azure security expertise, and a proactive mindset. If you enjoy impactful, visible work in a fast-growing fintech environment, apply to join our diverse

Qualifications

• Hands-on SIEM experience, Microsoft Sentinel preferred; other platforms ok.
• Azure security across Defender for Cloud, Entra ID, networking, and CSPM.
• Infrastructure-as-code with Terraform or Bicep in security context.
• Experience driving vulnerability remediation with engineering teams.
• Familiarity with data-loss-prevention controls.
• Awareness of AI security and securing AI workloads or tooling.
• Ability to articulate security risk via threat modelling to engineers/products.
• Growth mindset and curiosity to learn continuously.
• SC-200 certification or equivalent.
• Proficiency in KQL for detection and hunting.
• Experience in a fintech/financial services environment.

Responsibilities

• Own and operate alerting/monitoring during transition and maintain steady detection/response.
• Maintain and improve Microsoft Sentinel deployment: write/detect rules, manage data connectors, reduce noise.
• Operate Defender XDR/Defender for Cloud: policy mgmt and posture recommendations.
• Extend automated security checks in delivery pipelines (shift-left).
• Drive down time-to-fix on vulnerabilities; coordinate remediation with squads.
• Support data-loss-prevention controls to reduce data exfiltration risk.
• Safeguard AI usage: secure AI workloads and data exposure controls.
• Investigate suspicious activity surfaced by Sentinel/Defender; triage/elevate/contain as needed.
• Support incident response: containment, evidence gathering, post-incident review.
• Contribute to detection-as-code and IaC for security tooling (Terraform/Bicep).
• Coordinate penetration test engagements and work with teams to remediate.

Skills

SIEM experience

Azure security

IaC (Terraform/Bicep)

Vulnerability remediation

DLP controls

AI security

Threat modelling

Growth mindset

SC-200

KQL

Fintech exposure

Job description

Flagstone is seeking a senior security engineer to own and evolve cloud security, detection tooling, and incident response across Azure. You’ll operate Microsoft Sentinel, Defender for Cloud, and contribute to detection-as-code while coordinating pen tests and remediation with multiple engineering squads.

You’ll bring hands-on SIEM experience, Azure security expertise, and a proactive mindset. If you enjoy impactful, visible work in a fast-growing fintech environment, apply to join our diverse