Jonathan
Grenald
Cybersecurity Leader · Engineer · Architect
Senior Cybersecurity Engineer with 10+ years securing IT infrastructure on-premises and cloud. Specializing in resilient security architectures, threat intelligence, and embedding security into the SDLC — bilingual English/Spanish.
Who I Am
Professional Summary
Senior Cybersecurity Engineer with 10+ years of experience specializing in securing IT infrastructure both on-premises and in the cloud, email systems, networks, and applications. I design and implement resilient security architectures that protect critical assets while enabling operational efficiency.
My Edge
With a proven track record identifying vulnerabilities, deploying advanced defense strategies, and leading cross-functional teams, I bring both offensive and defensive expertise. Understanding attacker techniques adds real-world versatility to my security architecture decisions — delivering measurable results across every engagement.
Technical Skills
Cybersecurity Domains
Security Tools
Infrastructure & Platforms
Scripting & DevSecOps
Languages
Frameworks & Standards
Professional Experience
- Reduced cloud vulnerability exposure by 40% via WAF and attack surface monitoring.
- Decreased phishing incidents by 35% deploying advanced email security with DKIM/SPF/DMARC hardening.
- Led secure code analysis with 50+ developers, embedding security into the SDLC and promoting shift-left culture.
- Drove risk assessments and threat modeling reducing overall risk scores by 35%.
- Served as primary SOC point of contact coordinating incident response with low MTTR.
- Encrypted and tracked 300+ devices with full IT asset inventory management.
- Directed firewall administration reducing unauthorized access attempts by 60%.
- Managed enterprise-wide patching program lowering vulnerability exposure windows.
- Led OS modernization: VMware, CentOS, RHEL 6 and legacy Windows Server migrations to current versions.
- Designed cross-site backup & replication for 150+ servers using Veeam and VMotion.
- Improved issue detection speed by 40% through advanced monitoring for open-source infrastructure.
- Established standardized server baselines improving deployment consistency across Windows and Linux.
- Administered 700+ physical and virtual servers, patching vulnerabilities and improving performance.
- Reviewed and hardened shared folder permission security across the organization.
- Diagnosed and resolved complex networking issues ensuring stable and secure connectivity between server rooms.
- Assessed server and service performance, delivering insights influencing strategic infrastructure decisions.
- Designed and built full IT infrastructure from zero covering five business sites: VLAN segmentation, VoIP, and firewalls.
- Led technical support team improving SLA adherence and end-user satisfaction.
- Ticket management and effective support for 200+ users. IT Staff of the Year 2012.
- Configured Cisco routers for all bank branches; participated in high-availability migrations.
Education & Certifications
Recognitions
IT Staff Member of the Year
Recognized at Metrobank S.A. in 2012 for outstanding technical performance, initiative, and contribution to critical infrastructure projects.
Merit-Based Government Scholarship
Awarded a scholarship to Tianjin University, China, based on academic excellence and professional work experience — a highly competitive national selection.
Bilingual Security Leader
Full professional proficiency in English and Spanish (C1/C2), enabling direct leadership of multinational security teams and cross-border compliance engagements.
Security Intel Hub
A dedicated intelligence platform built alongside this portfolio — aggregating live cybersecurity news from the last 30 days and the most-starred open-source security tools on GitHub. No subscriptions, no logins, updated on demand.
Live Cyber News
Real-time stories from Hacker News filtered to the last 30 days — auto-classified into Vulnerabilities, Breaches, Malware, Policy, and Research.
Infosec Repositories
Top open-source security tools from GitHub ranked by stars — pentesting frameworks, CTF tools, threat intelligence platforms, and more.
Smart Filtering
Filter by category, refresh on demand, and browse with both English and Spanish support — bilingual by design, like everything I build.
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Let's Connect
Open to New Opportunities
For security reasons, direct contact information is not publicly displayed. Connect on LinkedIn for professional inquiries, collaboration opportunities, or to discuss cybersecurity challenges.
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