Vulnerability scanners: How to choose the right tool and effectively manage the results?

Regular vulnerability scanning is an absolute foundation and one of the most important processes in any mature cyber security program. It can be likened to periodic preventive medical checkups. Just as we regularly check our blood pressure and cholesterol levels to detect potential health problems early, we should regularly “scan” our IT infrastructure for digital “diseases” – software vulnerabilities, configuration errors and other weaknesses that can be exploited by attackers. A vulnerability scanner is our primary stethoscope and X-ray machine in this process.

However, buying and running a scanner is only the beginning of the journey, not the end. The market for these tools is vast and varied, and choosing the wrong solution can lead to frustration and a false sense of security. Moreover, even the best scanner is useless if its results – often numbering in the hundreds or thousands of identified “problems” – are not integrated into an efficient, repeatable process of analysis, prioritization and removal. This article is a practical guide to help you understand what the different types of scanners are, what to look for when choosing one and, most importantly, how to turn raw report data into real security enhancements for your company.

What is a vulnerability scanner and what role does it play in a cyber security program?

A vulnerability scanner is an automated tool designed to proactively examine computer systems, networks or applications to identify known vulnerabilities in them. It acts like a digital auditor that systematically checks the target under investigation against a huge, constantly updated database of known vulnerabilities (CVEs), configuration errors and weaknesses.

The scanner plays a key role within the broader Vulnerability Management program. Its job is to provide a first, broad but automated layer of information about potential vulnerabilities. It allows for a quick “scan” of hundreds or thousands of systems and an overall picture of the “health” of the entire infrastructure.

Note, however, that a scanner is not the same as a penetration test. A scanner identifies potential vulnerabilities based on signatures and patterns. A penetration test goes a step further and tries to proactively exploit these vulnerabilities to confirm whether they actually pose a real risk. Thus, scanning is an essential, regular preventive test, while pentest is a specialized test commissioned for in-depth verification.

What are the main categories of vulnerability scanners and how do they differ?

The market for scanners can be divided into several main categories, each specialized for examining a different type of target. Choosing the right category is the first and most important step.

• Network infrastructure scanners: This is the most classic and broadest category. These tools (e.g. Nessus, Qualys, OpenVAS) specialize in scanning networks for vulnerabilities in operating systems, network services (WWW, FTP, SMB), network devices and configuration errors.
• Web Application Scanners (DAST): Dedicated tools for testing web application security “from the outside in.” They simulate user and hacker actions in an attempt to find application-specific vulnerabilities such as SQL Injection, Cross-Site Scripting (XSS) or logic flaws (e.g. Netsparker/Invicti, Acunetix, Burp Suite Pro).
• Source code scanners (SAST): Tools that analyze an application’s source code “from the inside,” looking for patterns in it that indicate potential vulnerabilities, even before the application is launched.
• Software Composition Scanners (SCAs): Tools that analyze a project for vulnerabilities in the libraries and open-source components used.

This article focuses mainly on the first two, the most operational categories.

What to look for when choosing a scanner for network infrastructure and servers?

When choosing a scanner for a general infrastructure survey, there are several key factors to consider.

Vulnerability database coverage and quality: This is the heart of any scanner. It’s important to check how quickly a vendor adds newly discovered vulnerabilities (CVEs) to the database and the breadth of technologies being checked. Market leaders such as Tenable (maker of the Nessus scanner) and Qualys update their databases almost daily. OpenVAS is also a good, free starting point.

Support for authenticated scanning: This is an absolutely key feature. The scanner must be able to log into the systems under investigation (using the credentials provided) to examine them “from the inside.” This allows for much more accurate identification of missing patches and configuration errors.

Deployment and licensing model: Do you need an on-premise or cloud solution? How is the tool licensed – from number of IP addresses, number of scans or number of users? What is the quality and availability of technical support?

Integration and reporting capabilities: Can the scanner integrate with your ticketing system (e.g., Jira) to automate the task delegation process? Does it generate clear, useful reports for administrators and managers?

How to interpret the scan results and CVSS risk assessment system?

A scanner report can contain hundreds or thousands of identified vulnerabilities. The key to managing them effectively is prioritization. Not all vulnerabilities are created equal – some are trivial to exploit and lead to full system compromise, while others are purely theoretical.

The industry standard for assessing the criticality of vulnerabilities is CVSS (Common Vulnerability Scoring System). It is an open, standardized method that assigns each vulnerability a score on a scale of 0.0 to 10.0, where 10.0 indicates the highest criticality. The CVSS score is calculated based on a number of factors, such as:

• Attack vector: Can the vulnerability be exploited remotely over the network, or does it require local access?
• Complexity of the attack: Is the attack simple to carry out or does it require specialized conditions?
• Required credentials: Does the attacker not need any credentials or does he/she need to be already authenticated?
• Impact on confidentiality, integrity and availability.

Typically, vulnerabilities are divided into several levels: Critical (9.0-10.0), High (7.0-8.9), Medium (4.0-6.9) and Low (0.1-3.9). The IT team should focus on fixing Critical and High vulnerabilities first.

What is the difference between a non-authenticated scan and an authenticated scan?

Unauthenticated Scan: In this mode, the scanner operates from the perspective of an external, anonymous attacker. It examines the system “from the outside,” checking what ports are open, what services are running on them and whether they respond in a way that indicates a known vulnerability. This simulates an attack carried out by someone with no credentials.

Authenticated Scan / Credentialed Scan: In this mode, the scanner obtains credentials (login and password or SSH key) for an account on the system under investigation (usually an account with read privileges). Once logged in, the scanner can examine the system “from the inside.” It has access to a list of installed software and its exact versions, a list of installed patches, detailed configuration files and a lot of other information that is invisible from the outside.

Authenticated scanning is incomparably more accurate and valuable. It can accurately identify missing security patches and configuration errors, which is impossible in non-authenticated mode. It also generates far fewer false alarms. Non-authenticated scanning is good for investigating an external perspective, but it is authenticated scanning that is the foundation of a mature internal vulnerability management program.

How does nFlo help implement and manage an effective vulnerability scanning program?

At nFlo, we understand very well that buying a scanner is only the first, simplest step. Real value and real security are born from a mature, repeatable process that transforms raw report data into patched systems. That’s why we offer comprehensive support throughout the vulnerability management lifecycle.

For companies that want to manage the process themselves, we offer consulting services for selecting, implementing and configuring the right vulnerability scanner. We help you match the technology to your needs and budget, and then configure it optimally, including setting up authenticated scanning and tuning policies to minimize false positives.

However, for most organizations, the most cost-effective and operationally efficient model is our Managed Vulnerability Management service. With this service, we take on the entire burden. Our team, using market-leading technology, regularly scans your infrastructure, but our work begins where the scanner’s work ends. We manually verify the results, eliminate false positives and enrich the data with business context. As a result, you don’t get a report from us with thousands of items, but a prioritized, expert-verified list of real, confirmed vulnerabilities, ready to be handed over to your IT team. What’s more, our pentesters can then verify which of these vulnerabilities are actually exploitable, separating theoretical from practical risks.