Senior Security Engineer · Dublin, Ireland

Kirubakaran
Jayakumar

CISSP · CISM  ·  9+ Years at the Intersection of Attack & Defence

Cyber Security Engineer specialising in SIEM engineering, threat detection, incident response, cloud security, and VAPT — bridging offensive and defensive security operations across enterprise and cloud environments.

View Experience Let's Connect
01 / About

Building Security
from the Inside Out

Kirubakaran Jayakumar
Kirubakaran Jayakumar

A security engineer who thinks like an attacker and defends like a practitioner — combining red and blue team perspectives to build detection strategies that actually hold up in the real world.

Currently at Nitro as a Senior Security Engineer, I lead threat detection engineering, SIEM operations, and security programme initiatives, building out detection maturity and driving measurable risk reduction.

My work spans SIEM implementation and tuning (Splunk, AlienVault), threat hunting, incident response, penetration testing, and compliance programmes across ISO 27001, PCI DSS, SOC 2, DORA, and HIPAA. I automate wherever possible — Python is my go-to for enrichment pipelines, triage scripts, and detection logic.

Based in Dublin, Ireland. MSc in Cybersecurity from the National College of Ireland.

📍
Location
Dublin, Ireland
🏢
Current Role
Senior Security Engineer · Nitro
🎓
Education
MSc Cybersecurity · BEng Computer Science
🛡️
Specialisations
SIEM, Threat Detection, IR, Threat Hunting, VAPT
📋
Compliance
ISO 27001 · PCI DSS · SOC 2 · DORA · HIPAA
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Automation
Python · Splunk SPL · PowerShell · SOAR
02 / Capabilities

Technical Arsenal

A deep, hands-on toolkit built across enterprise environments — from SOC monitoring and threat intel platforms to cloud security and compliance tooling.

01
SIEM & Monitoring
Datadog AlienVault USM Wazuh Microsoft Sentinel Power BI Elastic Stack
02
Threat Detection & Hunting
MITRE ATT&CK Sigma Rules YARA Threat Intel MISP OpenCTI Recorded Future
03
Incident Response & IR
IR Playbooks Forensics CrowdStrike Microsoft Defender Trellix HX AnyRun
04
Penetration Testing
VAPT Web App Security Mobile SAST/DAST Network Assessment OWASP OSSTMM
05
Cloud & Infrastructure
AWS Kubernetes Wiz Axonius CrowdStrike Cloud Docker
06
Email & Network Security
Microsoft ATP Cofense Vision Cofense Triage Checkpoint FW Forcepoint Proxy Trellix IPS
07
Automation & Scripting
Python Splunk SPL PowerShell SOAR REST APIs KQL
08
Compliance & GRC
ISO 27001 PCI DSS SOC 2 DORA HIPAA NIST CSF QTSP
03 / Experience

Career Timeline

N
Nitro · Dublin, Ireland
Oct 2024 – Present
Senior Security Engineer Apr 2026 – Present
Security Engineer Oct 2024 – Mar 2026
  • Led threat detection engineering and SIEM operations across Datadog and cloud-native tooling, reducing alert noise from 800+/month to ~200 while maintaining high-fidelity detection coverage.
  • Deployed Bronto logging solution to close critical visibility gaps in the security monitoring stack; architected and maintained detection use cases aligned to MITRE ATT&CK TTPs.
  • Led ISO 27001 implementation programme — achieved certification with zero non-conformities.
  • Lead the infrastructure vulnerability management and external attack surface programme, working closely with engineering, product, and business stakeholders to drive risk reduction at scale.
  • Research and assess public and private vulnerability disclosures and active exploit code, translating technical findings into clear impact assessments across infrastructure, services, and applications.
  • Own end-to-end vulnerability triage and prioritisation — scoping severity and blast radius, coordinating remediation with engineering teams, and tracking findings through to verified closure.
  • Built automation to enrich and route vulnerability tickets with contextual detail, reducing manual triage effort and ensuring consistent tracking of hardening activities and exception records.
  • Triage, verify, and report on inbound bug bounty submissions from external security researchers, coordinating disclosure and remediation with internal engineering teams.
  • Own and drive company-wide security OKRs as DRI, delivering monthly risk posture updates directly to the CTO with clear metrics and programme progress.
  • Maintain and improve security runbooks, playbooks, and operational documentation; serve in a global on-call rotation and lead surge response for critical exposures.
  • Actively mentor team members, supporting skill development and contributing to a strong security engineering culture.
Datadog Bronto Vuln Management Attack Surface CrowdStrike Wiz AWS ISO 27001 MITRE ATT&CK Bug Bounty
S
Smurfit WestRock · Ireland
Apr 2020 – Oct 2024
Cyber Security Analyst
  • SIEM Implementation Lead — deployed and configured Splunk for enterprise-scale log ingestion and correlation.
  • Led cybersecurity asset management programme using Axonius for comprehensive asset visibility.
  • Developed advanced detection use cases translating business risk into actionable SIEM logic.
  • Spearheaded incident response for critical events, including war room coordination with senior leadership.
  • Enhanced email security posture using Microsoft ATP, Cofense Vision, and Cofense Triage.
  • Established KPI dashboards and security metrics reporting for management and regulatory audiences.
  • Led vulnerability management programme including scan scheduling, prioritisation, and patching tracking.
Splunk Axonius Microsoft Defender Cofense Trellix Vulnerability Mgmt
SC
SecuriCentrix · Ireland · MSSP
Nov 2019 – Apr 2020
Information Security Analyst
  • Integrated client infrastructure into the MSSP SOC using AT&T USM Anywhere.
  • Managed security operations for critical payment gateway clients with strict SLA and compliance requirements.
  • Delivered comprehensive weekly security posture reports across the client portfolio.
AlienVault USM SOC Operations PCI DSS
SG
Sogeti part of Capgemini · Ireland
Jun 2019 – Aug 2019
Cyber Security Research Intern
  • Automated Android penetration testing via static code analysis scripting.
  • Improved threat modelling process by implementing IriusRisk tool into the workflow.
  • Delivered security awareness session on secure coding practices for development teams.
Mobile VAPT Threat Modelling Python
W
Wity Technology Corporation · India
Dec 2017 – Jul 2018
Security Analyst
  • Deployed and managed Sophos MDM and endpoint protection across client environments.
  • Monitored security threats and risk-mitigation activities across client infrastructure, including timely triage of alerts and escalation management.
  • Administered network infrastructure and maintained security tooling in line with evolving threat landscape.
Sophos Endpoint Security Network Security
TV
Tevel formerly InternetTechies Solutions Pvt Ltd · India
Sep 2016 – Dec 2017
Information Security Analyst
  • Conducted web and mobile application security testing (SAST/DAST) using OWASP and OSSTMM methodologies.
  • Performed network vulnerability assessments and developed remediation plans for enterprise clients.
  • Conducted risk assessments and recommended security enhancements aligned to industry standards.
VAPT OWASP OSSTMM Network Security
04 / Credentials

Certifications

CISSP
CISSP
Certified Information Systems Security Professional
ISC²
● Active
Verify on Credly ↗
CISM
CISM
Certified Information Security Manager
ISACA — 2024
● Active
Verify on Credly ↗
CEH
CEH
Certified Ethical Hacker
EC-Council — 2016
● Achieved
MSc
MSc
Master of Science — Cybersecurity
National College of Ireland · 2019
● Achieved
05 / Contact

Get in Touch

Open to connecting with security professionals, discussing threat detection challenges, or exploring opportunities aligned with my expertise. Whether it's a technical collaboration or a career conversation — reach out.

Available for conversations · Based in Dublin, Ireland
✉
Email [email protected]
in
LinkedIn linkedin.com/in/kirubakaran-jayakumar
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Blog blog.mr0k.com