Network Scanning during Pen-testing

Network scanning is a fundamental technique used in cybersecurity to identify active devices, assess their security, and maintain the integrity of an organization's network infrastructure. It involves systematically probing a network to discover hosts, devices, and the services running on them. This process is crucial for identifying vulnerabilities that could be exploited by attackers.

Why Network Scanning is Important

Network scanning helps in:

1. Identifying Active Devices: Detecting all devices connected to the network, including unauthorized ones.
2. Assessing Network Health: Monitoring the network’s performance and identifying any anomalies.
3. Discovering Vulnerabilities: Finding weak points that could be exploited by cyber threats.
4. Compliance: Ensuring that the network meets regulatory requirements and standards.

How Network Scanning Works

Network scanning generally involves the following steps:

1. Network Mapping: Creating a visual representation of the network's structure.
2. Host Discovery: Identifying all the active devices on the network.
3. Service Detection: Determining what services each device is running.
4. Vulnerability Detection: Identifying potential security risks on each device.

Common tools used for network scanning include Nmap, Nessus, and OpenVAS. These tools offer various functionalities, from simple ping sweeps to complex vulnerability assessments.

Types of Network Scanning

There are several methods and types of network scanning, each serving different purposes:

1. Ping Sweep: A simple method to discover live hosts by sending ICMP echo requests.
2. Port Scan: Examining open ports on a host to determine available services.
3. OS Detection: Identifying the operating system running on a host.
4. Service Version Detection: Determining the versions of services running on open ports.

Network Scanning vs. Other Types of Scanning

It’s important to distinguish network scanning from other types of scanning in cybersecurity:

1. Port Scanning: Focuses specifically on identifying open ports and the services running on them. While network scanning can include port scanning as a step, the latter is more targeted and detailed in its approach to understanding service availability and potential vulnerabilities.

2. Vulnerability Scanning: Involves scanning systems to identify known vulnerabilities. It uses a database of known flaws and matches these against the network's devices and applications. This type of scanning is more about identifying specific weaknesses rather than just mapping the network.

3. Web Application Scanning: Specifically targets web applications to identify security weaknesses like SQL injection, cross-site scripting (XSS), and other web-specific vulnerabilities.

4. Compliance Scanning: Ensures that the network and systems meet certain regulatory or industry standards, such as PCI-DSS or HIPAA.

While network scanning provides a broad overview of the network’s structure and devices, other scans delve deeper into specific areas to provide detailed security assessments.

Best Practices for Network Scanning

To effectively perform network scanning, follow these best practices:

1. Regular Scanning: Conduct scans regularly to keep up with changes in the network.
2. Use Multiple Tools: Employ various scanning tools to get comprehensive results.
3. Non-Intrusive Scanning: Use non-intrusive methods during business hours to avoid disrupting network operations.
4. Document Findings: Keep detailed records of scans and findings for future reference and compliance.
5. Update Tools: Ensure that scanning tools and their databases are up to date to recognize the latest vulnerabilities.
6. Follow Up on Results: Act on the findings by patching vulnerabilities and updating security measures.

Conclusion

Network scanning is a critical activity in cybersecurity, providing insights into the network's layout, active devices, and potential vulnerabilities. While it shares similarities with other scanning techniques like port scanning and vulnerability scanning, network scanning serves as the foundational step in understanding and securing an organization's network. By following best practices and using a combination of tools and methods, organizations can effectively monitor and protect their networks from cyber threats.