Download Nessus Professional

[Caleb Nelands]

AnOpenVAS vs. Nessus comparison is a battle between two top leaders in the vulnerability scanning market. Each tool has its strengths and weaknesses, but deciding between them will likely come down to your specific use case. Nessus is best for companies that want more of an off-the-shelf vulnerability scanning solution, while the open source OpenVAS is best for organizations that want more customization and integrations.

Open Vulnerability Assessment System (OpenVAS) and Nessus both function in a similar fashion. After discovering points of weakness, the scanners compare them against a database of known vulnerabilities, identify and rank the discovered security gaps (usually in a summarized report) by severity or risk score, and offer advice or actions to take toward remediation.

Vulnerability scanners comprise a diverse and divergent set of solutions, from tools for software penetration testing (pentesting) to suites that identify and classify IT infrastructure weak points, quantify related cyber risks, and prescribe mitigation strategies and activities to close the discovered security gaps.

Both OpenVAS and Nessus fall into that second category: tools that discover weak points in networked environments like firewalls, applications, and services before cyber attackers seize the opportunity to compromise exposed IT assets. By systematically probing for weaknesses and security flaws, these vulnerability scanners can identify, classify, and enumerate exploitable targets like open ports, services, software versions, and more to help security professionals correct them in an ongoing, timely manner.

It uses a client-server architecture consisting of two main components: the OpenVAS Scanner and the OpenVAS Manager. The OpenVAS Scanner performs the actual vulnerability scanning tasks. OpenVAS Manager orchestrates and manages the scanning process, including scheduling scans, collecting results, and generating reports.

When a vulnerability scan is initiated, OpenVAS Manager communicates with the OpenVAS Scanner to execute the scan according to configured parameters. The scanner systematically probes the target systems or networks, identifying potential vulnerabilities by actively testing for known security issues.

Finally, the OpenVAS Manager aggregates the results, prioritizes vulnerabilities based on severity and potential impact, and generates detailed reports that provide actionable insights for remediation efforts, empowering organizations to proactively manage and mitigate security risks.

Though once available as a free, open source download, the no-cost version of Nessus is primarily available these days as Tenable Nessus Essentials, a scaled down version of the leading vulnerability scanner. Nessus Essentials allows users to scan environments up to 16 IP addresses per scanner, max.

During the scanning process, Nessus employs a variety of techniques to identify vulnerabilities, including network scanning, port scanning, service enumeration, and vulnerability checks based on extensive plugins. These plugins contain checks for thousands of known vulnerabilities across diverse platforms and applications.

As the scan progresses, Nessus collects detailed information about discovered vulnerabilities, prioritizing them based on severity and potential impact. Upon completing the scan, Nessus generates comprehensive reports that provide actionable insights into the security posture of the scanned environment, enabling organizations to proactively address weaknesses and mitigate security risks effectively.

While both solutions gained their popularity in open source form, their maintainers are decidedly commercial in nature. Greenbone Networks AG, the developer of the full-featured OpenVAS vulnerability scanner, is a leading German security vendor with a long history in vulnerability analysis solutions for enterprises.

In contrast, authenticated scanning requires direct network access via authenticated means, employing protocols and technologies like remote desktop protocol (RDP), virtual private networks (VPNs), virtual network computing (VNC), and secure shell (SSH). Direct access scanning allows for deeper, more comprehensive scans due to the level of penetration into the target IT environment, enabling security professionals to emulate attackers looking to exploit application and operating system vulnerabilities on endpoint systems and internal servers.

From a pricing perspective, OpenVAS vs. Nessus is somewhat of an apples-to-oranges comparison. OpenVAS, as a free vulnerability scanning solution, certainly takes the prize in the eyes of the budget-conscious user. Its source code can be downloaded from GitHub and modified at will, making it an ideal tool for the security professional with development chops. Teams looking to develop a bespoke vulnerability scanning solution without having to start from scratch will also appreciate its no-cost offering.

The vulnerability scanner market is bigger than two tools, and alternatives to OpenVAS and Nessus range from high-end commercial offerings like Rapid7 Nexpose and SonarSource to lower cost options like Burp Suite and MetaSploit. Seasoned security professionals may even opt to use free penetration testing suites like Kali Linux, which require substantial technical expertise but allow for virtually unlimited power under-the-hood when it comes to scanning capabilities.

In terms of pricing, I looked at the initial price tag as well as the overall cost of ownership and management, keeping in mind that open source tools more often carry the hidden cost of required technical expertise and management overhead.

Security professionals looking to acquire a competent vulnerability scanner may not necessarily favor a streamlined user interface (UI) and pleasant front-end experience over functionality. That said, firms employing a more skills-diverse security staff may benefit greatly from an easy-to-use vulnerability scanner. I evaluated OpenVAS and Nessus from both these angles.

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Managing Nessus Professional API tokens and keys securely can be challenging. However, we can automate the process of acquiring tokens, securely storing them, and using them for API interactions. Nessus Professional is hosted locally using an mTLS network.

The extracted token from the first response can now be used it to perform the next request that creates API keys. Creating API keys makes the overall automation process much simpler than attempting to emulate a real user session using login session tokens.

Historically, storing sensitive tokens directly in code has been a common practice, but this method is inherently insecure. Tokens, when embedded in scripts or applications, can be exposed through version control systems or if the codebase is accessed by unauthorised parties.

Next, in an attempt to remove tokens and passwords from code by incorporating HashiCorp Vault as our secrets manager, however we haven't achieved our goal as Vault credentials are still held in code.

As you can see in the above code, this integration introduces a new conundrum: the Vault itself requires authentication. Whether we fetch Vault credentials from environment variables or hard-code them into our scripts, we find ourselves at an impasse. Neither method is entirely secure; both could potentially lead to exposure of these credentials if not handled with care.

It's clear that our journey doesn't end here. In pursuit of a more secure solution, our narrative will evolve to include the implementation of SPIFFE and SPIRE. These tools are designed to dynamically provide identities to software systems in a wide array of environments, including cloud, containerised, and even traditional infrastructure. By leveraging SPIFFE and SPIRE, we aim to solve the issue of securely authenticating services without relying on static, long-lived credentials.

Next time we deep dive Spiffe Spire, where we will dive into the installation of SPIFFE and SPIRE to secure the foundational layer of our authentication system. This project forms the basis to securing a LlamaIndex installation that I am building over the coming weeks.

Originally launched as an open source tool in 1998, its enterprise edition became a commercial product in 2005. Nessus now encompasses several products that automate point-in-time vulnerability assessments of a network's attack surface, with the goal of enabling enterprise IT teams to stay ahead of cyber attackers by proactively identifying and fixing vulnerabilities as the tool discovers them, rather than after attackers exploit them.

Nessus identifies software flaws, missing patches, malware, denial-of-service vulnerabilities, default passwords and misconfiguration errors, among other potential flaws. When Nessus discovers vulnerabilities, it issues an alert that IT teams can then investigate and determine what -- if any -- further action is required.

Nessus is known for its vast plugin database. These plugins are dynamically and automatically compiled in the tool to improve its scan performance and reduce the time required to assess, research and remediate vulnerabilities. Plugins can be customized to create specific checks unique to an organization's application ecosystem.

Nessus contains a feature called Predictive Prioritization, which uses algorithms to categorize vulnerabilities by their severity to aid IT teams in determining which threats are most urgent to address. Each vulnerability is assigned a Vulnerability Priority Rating (VPR), which uses a scale from 0 to 10, with 10 being the highest risk, to rate its severity: critical, high, medium or low. IT teams can also use pre-built policies and templates to quickly find vulnerabilities and understand the threat situation.

Another Nessus feature is Live Results, which performs intelligent vulnerability assessment in offline mode with every plugin update. It removes the need to run a scan to validate a vulnerability, creating a more efficient process to assess, prioritize and remediate security issues.

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