Senior Cloud Security Engineer (Contract) - Azure & SIEM

Jackalope Digital LLC; Greater London; Hybrid; GBP 101,000 - 138,000; Full time

Job summary

Flagstone is seeking a senior security engineer for a contract role with hands-on experience across cloud security, SIEM, and incident response. You will own detection capabilities, optimize Defender XDR/Cloud, and contribute to security tooling and threat modelling.

The role requires practical Azure security expertise, IaC skills with Terraform or Bicep, and a focus on reducing risk in a fintech environment.

Qualifications

• Hands-on SIEM experience, ideally Microsoft Sentinel; equivalent platforms considered.
• Practical Azure security experience across Defender for Cloud, Entra ID, Azure networking, and cloud security posture management.
• Experience writing infrastructure-as-code using Terraform or Bicep in a security engineering context.
• Experience driving vulnerability remediation cycles with engineering squads.
• Familiarity with data-loss-prevention controls.
• Familiarity with AI security considerations and/or using AI tooling to augment security engineering workflows.
• Ability to contribute to threat modelling and communicate security risk clearly to engineering and product audiences.
• SC-200 (Microsoft Security Operations Analyst) certification.
• KQL proficiency for detection rule authoring and threat hunting.
• Experience working in a similar fintech or financial services environment

Responsibilities

• Own and operate alerting and monitoring capabilities, maintaining steady detection and response.
• Maintain and improve Microsoft Sentinel deployment: write/tune detection rules, manage data connectors, reduce alert noise.
• Operate and optimize Defender XDR and Defender for Cloud: policy management and posture recommendations.
• Maintain and extend automated security checks in delivery pipelines (Shift-Left).
• Drive down time-to-fix on known vulnerabilities, coordinating with engineering squads.
• Support data-loss-prevention controls to reduce data exfiltration risk.
• Support safeguards around AI usage, securing AI workloads and data exposure.
• Investigate suspicious activity surfaced through Sentinel and Defender: triage/elevate/contain.
• Support incident response: containment, evidence gathering, post-incident review.
• Contribute to detection-as-code and infrastructure-as-code (Terraform or Bicep).
• Coordinate penetration test engagements and prioritise remediation with engineering teams.

Skills

SIEM

Microsoft Sentinel

Azure security

Threat modelling

KQL

Incident response

Vulnerability remediation

Tools

Terraform

Bicep

Defender for Cloud

Entra ID

Defender XDR

Job description

Flagstone is seeking a senior security engineer for a contract role with hands-on experience across cloud security, SIEM, and incident response. You will own detection capabilities, optimize Defender XDR/Cloud, and contribute to security tooling and threat modelling.

The role requires practical Azure security expertise, IaC skills with Terraform or Bicep, and a focus on reducing risk in a fintech environment.