Senior Security Engineer

Bestman Solutions; Greater London; On-site; GBP 89,000 - 156,000; Full time

Job summary

Bestman Solutions. International in London, United Kingdom, seeks a Senior Security Engineer to lead design and enhancement of security operations for a global investment firm.

The role focuses on threat detection, tooling improvements, automation, and AI integration within security operations. You will own detection engineering across SIEM/XDR, conduct proactive threat hunting, and support complex investigations while collaborating with IT, Legal, HR and senior stakeholders to drive operational

Qualifications

• 6+ years of experience in security engineering or operations.
• Hands-on with SIEM/XDR technologies and query languages (KQL/SPL).
• Automation skills with Python and PowerShell.

Responsibilities

• Design and optimise detection rules across SIEM and XDR.
• Improve log-source coverage and alert accuracy.
• Develop security automation using Python/PowerShell.
• Review tooling for configuration, integration and operational improvements.
• Threat hunting across endpoint, identity, cloud and SaaS environments.
• Support incident response and investigations.
• Apply AI-assisted security capabilities for better detection and response.
• Develop detections for AI-related threats (prompt injection, data leakage, AI phishing).
• Collaborate with IT, Legal, HR and leadership on incidents and improvements.

Skills

SIEM/XDR

KQL

SPL

CrowdStrike

Python

PowerShell

Threat hunting

Endpoint security

MITRE ATT&CK

AI in security

Tools

CrowdStrike

Microsoft 365 security

Job description

Senior Security Engineer – Security Operations | 6-Month Contract

We’re working with a global investment firm looking for a Senior Security Engineer to support the continued development and improvement of its security operations capability.

This is a hands‑on engineering role focused on strengthening threat detection, improving existing security tooling, expanding automation and integrating AI into security operations.

The organisation already has a mature security technology environment and is looking for someone who can take ownership of technical improvements, work independently and contribute to both engineering initiatives and operational security activities.

Responsibilities

• Design, build and optimise detection rules and threat-hunting queries across SIEM and XDR platforms.
• Improve log-source coverage, telemetry quality and alert accuracy, reducing unnecessary noise.
• Develop security automation and integrate existing tools using Python and/or PowerShell.
• Review and optimise security tooling, identifying opportunities to improve configuration, integration and operational effectiveness.
• Conduct proactive threat hunting across endpoint, identity, cloud and SaaS environments.
• Support incident response activities, including complex and sensitive security investigations.
• Apply AI-assisted security capabilities to improve threat detection, investigation and response.
• Develop detections for emerging AI-related threats, including prompt injection, data leakage and AI-enabled phishing.
• Work closely with IT, Legal, HR and senior stakeholders on security incidents and operational improvements.

Requirements

• Strong background in security engineering, detection engineering, security operations or incident response, typically with 6+ years of relevant experience.
• Hands‑on experience with SIEM/XDR technologies and query languages such as KQL, SPL or CrowdStrike LogScale.
• Experience with endpoint security technologies, ideally including CrowdStrike, across Windows and macOS environments.
• Strong Microsoft 365 security experience, including investigating and responding to threats.
• Practical scripting and automation skills using Python and/or PowerShell.
• Experience integrating and optimising security tools within complex enterprise environments.
• Hands‑on experience with enterprise AI tools and AI-assisted security operations.
• Good understanding of threat intelligence, attacker techniques and frameworks such as MITRE ATT&CK.
• Strong communication skills, sound judgement and the ability to deliver independently.

This is an opportunity to work closely with senior security leadership in a sophisticated investment environment, with genuine scope to influence how security operations are engineered and improved.