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How can a simple open port scanner help you protect your cybersecurity?

The open port scanner is a tool that allows companies to inventory their assets and evaluate their perimeter security measures

In cybersecurity, often, the same technique or tool can be used to do good, i.e., improve an organization’s level of protection against a cyberattack, but also to carry out malicious actions. This is the case with the open port scanner.

Cybersecurity professionals resort to this tool to detect weaknesses in corporate devices. However, criminals also use the open port scanner for the same purpose: to try to identify potentially vulnerable services in a company’s security perimeter and to sneak into its systems.

Ports are important because they function as gateways that allow data to be sent and received between services. Ports can have three primary states:

  • Closed. In such a way that no data traffic can pass through them.
  • Filtered. These are ports that are open but whose traffic is filtered through the use of security mechanisms such as firewalls.
  • Open. These ports are accessible from the outside and can, therefore, be used by malicious actors to access a service.

In this article, we will explain open port scanning, how it can improve a company’s cybersecurity level, and how hostile actors use it to provoke security incidents.

Network scanning vs. port scanning

First, before delving into open port scanning, it is essential to establish the differences between this tool and network scanning. Both network scans and port scans are reconnaissance techniques used to identify assets in an infrastructure. So why aren’t they a single technique, and how do they differ?

  • Network scans allow the identification of active hosts, for example, by sending ICMP packets to determine whether a system has responded.
  • Port scans are used to determine the particular services exposed per system, such as a web server, SSH, etc.

Beyond their differences, both techniques are crucial to improving the cybersecurity of an organization’s technology infrastructure because:

  • They help identify the assets present in an infrastructure.
  • They are used to evaluate network segmentation.
  • They are beneficial when analyzing network and equipment firewall security policies.

What is an open port scanner?

In light of the above, what exactly is a port scanner? It is an active reconnaissance tool that allows one to analyze the existence of services exposed by a particular system.

Cybersecurity professionals use the open port scanner to simulate the establishment of a connection to specific ports and determine whether they are open, closed or filtered by a perimeter security system such as a firewall.

One of the additional features commonly available to an open port scanner is service fingerprinting techniques. These techniques identify specific products and software versions.

Currently, there are several classes of port scanners, but the most common are nmap and masscan. Both tools are notable because they have network and port scanning capabilities. Thus, using a single solution, performing both types of scanning to detect vulnerabilities and strengthen an organization’s security level is possible.

How can an open port scan improve a company’s cybersecurity?

Cybersecurity professionals use the open port scanner to perform three strategic actions in their work to protect organizations:

  1. Thanks to the open port scanner, it is possible to carry out an up-to-date inventory of hosts and services exposed at a particular time. Why is it so important to constantly update this inventory? When discussing a corporate infrastructure, we must understand that it is a changing environment in which new applications and services are periodically deployed to meet the organization’s needs. So, it is critical to check that new applications are not exposed and can be successfully attacked by malicious actors.
  2. The open port scanner is also extremely useful for performing one of the essential tasks of any corporate cybersecurity program: inventorying assets.
  3. Cybersecurity experts also use the open port scanner to evaluate a company’s perimeter security measures and network segmentation measures. This allows them to check their effectiveness and optimize them to prevent hostile actors from illegitimately accessing the corporate infrastructure.

Can criminals use the open port scanner against a company?

As we noted at the beginning of this article, the open port scanner is a tool with enormous potential in securing a company. Still, it can also be a dangerous tool for cybercriminals.

The experience accumulated by cybersecurity experts shows that malicious actors use port scanners when they want to attack an organization. What do they do?

  1. Employ an open port scanner to identify possible corporate applications or services exposed to the Internet or on the internal network.
  2. Determine if these services or applications may be affected by a vulnerability.
  3. Evaluate the network segmentation policy to identify other critical infrastructure assets to pivot to.

This information allows them to design and execute successful attacks and meet their malicious objectives.

Conclusions: an ally, which has to be framed in a global strategy

In short, the open port scanner is a very useful tool for protecting a company’s perimeter against cyberattacks and increasing its security.

However, its use must be part of a comprehensive security strategy in which cybersecurity services are available to protect an organization’s critical assets, manage vulnerabilities with maximum efficiency and prevent serious security incidents with extraordinarily severe economic, legal and reputational consequences.