Deirdre O'Callaghan
Senior Cyber Security Analyst | Threat Detection, Incident Response & Security Architecture
Cork
Professional Summary
Senior Cyber Security Analyst based in Cork with extensive experience protecting enterprise infrastructure across technology and financial sectors. Specialises in advanced threat detection, incident triage, and security operations maturity.
Skilled at translating complex technical telemetry into actionable risk mitigations, aligning monitoring workflows with ISO 27001 standards, and mentoring security teams in rapid threat response.
Professional Experience
Shannon River Technologies
Cork, Ireland
Lead Cyber Security Analyst
Mar 2020 – Present
- Direct Tier 2 and Tier 3 incident response investigations across multi-cloud and on-premises enterprise infrastructure.
- Engineer and fine-tune correlation rules within Splunk Enterprise Security, decreasing operational false positives by 38 percent.
- Coordinate incident post-mortems and remediation actions following high-severity security events, briefing executive risk committees.
- Facilitate quarterly purple team adversary simulation exercises to benchmark detection posture against the MITRE ATT&CK framework.
Lee Valley Financial Systems
Cork, Ireland
Senior Information Security Analyst
Jun 2014 – Feb 2020
- Supervised 24/7 security monitoring workflows for core electronic payments and commercial banking platforms.
- Executed routine vulnerability assessments using Qualys and enforced remediation timelines across engineering squads.
- Drafted standardized containment protocols, forensic triage playbooks, and regulatory breach notification procedures.
Bandon Data Networks
Cork, Ireland
Information Security Analyst
Jan 2010 – May 2014
- Monitored enterprise perimeter traffic using Snort and Wireshark to isolate anomalous lateral movement and exfiltration attempts.
- Conducted firewall change validations and privileged access reviews for client gateway environments.
Education
University College Cork
Bachelor of Science (Honours) · Computer Science · Cork, Ireland · First Class Honours · Sept 1983 – Jun 1987
Coursework centered on computer systems architecture, telecommunications, relational database systems, and data structures.
Key Projects
Enterprise SIEM Migration & Alert Optimization
Jan 2022 – Nov 2022
- Spearheaded the ingestion cutover of 14,000 corporate endpoints and cloud assets from legacy logging nodes to Splunk Cloud.
- Authored 65 custom alerting queries mapped to critical adversary behaviors, establishing verified alert pipelines within four months.
Core Competencies
Incident Response & Triage
SIEM Engineering (Splunk)
Threat Hunting & Detection
EDR & Endpoint Forensics
Vulnerability Management
MITRE ATT&CK Mapping
Network Traffic Analysis
ISO 27001 & NIS2 Alignment
Security Automation (Python)
Identity & Access Governance
Languages
English
C2
Irish
B2
Certifications
Certified Information Systems Security Professional (CISSP)
(ISC)2 · Apr 2015
Certified Information Security Manager (CISM)
ISACA · Nov 2018
GIAC Certified Incident Handler (GCIH)
GIAC Certifications · Jun 2023
Community & Mentorship
Southern Cyber Hub Ireland
Cork, Ireland · Sept 2021 – Present
- Technical Mentor
- Facilitate semi-annual practical workshops on log analysis and fundamental defensive tactics for tertiary students and career changers.