Cybersecurity | Network Security | Cloud Security

Building hands-on labs in AWS, Cisco networking, and malware traffic analysis

Identified and exploited insecure sudo configurations to escalate privileges to root on a Linux system.

• Analyzed /etc/sudoers for misconfigured NOPASSWD permissions
• Abused the less binary to execute shell commands
• Successfully gained root shell access
• Demonstrated impact of improper privilege management

🔗 Project Repository
https://github.com/mrtnzjhonatan/linux-privilege-escalation-sudo

Designed and implemented a Router-on-a-Stick network topology to enable inter-VLAN communication between segmented networks.
This lab demonstrates how Cisco networking can be practiced using Linux-based tools such as Dynamips, Dynagen, and VPCS without requiring physical hardware.

Key concepts demonstrated:

• VLAN segmentation
• Inter-VLAN routing
• 802.1Q trunk configuration
• Router subinterfaces
• Layer 2 and Layer 3 connectivity troubleshooting
• Cisco router and switch configuration in a Linux environment

🔗 Project Repository
https://github.com/mrtnzjhonatan/Router-on-a-Stick-VLAN-Network

Performed network traffic analysis on a compromised host using Wireshark to identify suspicious communications and potential Indicators of Compromise (IoCs).

The investigation focused on analyzing encrypted HTTPS traffic, inspecting TLS handshake metadata, reviewing DNS query behavior, and identifying command-and-control communication over the MQTT protocol.

Key findings included suspicious traffic associated with the Wikiloader malware family, including connections to potentially malicious domains and repeated DNS queries indicating persistent external communication.

Skills Demonstrated

• Network Traffic Analysis
• Wireshark Packet Inspection
• Threat Hunting
• DNS and TLS Analysis
• Identifying Indicators of Compromise (IoCs)

🔗 Project Repository
https://github.com/mrtnzjhonatan/network-traffic-analysis

Designed and deployed a segmented AWS network architecture using a VPC, public and private subnets, NAT Gateway, Internet Gateway, route tables, and Network ACL security controls.

Technologies AWS VPC • EC2 • NAT Gateway • Internet Gateway • Route Tables • Network ACLs

🔗 Project Repository
https://github.com/mrtnzjhonatan/aws-vpc-secure-infrastructure

🛡️ Cybersecurity Professional with hands-on experience in offensive and defensive security techniques. Ranked in the Top 1% on TryHackMe with over 215+ rooms completed and 29+ badges earned. I specialize in:

• 🔍 Threat Detection & Blue Teaming
• 🧠 Vulnerability Assessment & Exploitation
• 🐧 Linux Privilege Escalation
• 🛠️ Network & Web Application Pentesting

• ✅ Jr Penetration Tester (30h 40m, Completed June 2025): View Certificate
• ✅ Security Engineer: View Certificate
• ✅ Intro to Cyber Security: View Certificate
• ✅ Pre-Security: View Certificate

• Blue (EternalBlue exploit)
• Mr. Robot
• OWASP Top 10
• Linux Privilege Escalation

🧩 View all rooms: TryHackMe Profile

🛠️ Cybersecurity Labs Repo
📝 Write-ups, tools, and hands-on walkthroughs from TryHackMe rooms

• 🧑‍💼 LinkedIn: Jhonatan Martinez
• 💻 GitHub: @mrtnzjhonatan

I am actively advancing my cybersecurity knowledge through Hack The Box Academy. Below is a list of completed modules and badges demonstrating hands-on skills in networking, Linux, enumeration, and exploitation.

• 🧠 Learning Process
• 🚀 Intro to Academy
• 🐧 Linux Fundamentals
• 🌐 Network Enumeration with Nmap
• 🛡️ Introduction to Networking
• 💣 Using the Metasploit Framework
• 🐍 Introduction to Python 3
• 🔧 Network Foundations