Widely used cybersecurity tool designed for scanning systems and networks to identify vulnerabilities.
What is Nessus?
Nessus is a internal security scanning tool, which scans a computer and raises an alert if it discovers any vulnerabilities that malicious hackers could use to gain access to any computer you have connected to a network. It does this by running over 1200 checks on a given computer, testing to see if any of these attacks could be used to break into the computer or otherwise harm it. It scans for security holes and potential threats by running hundreds of checks against a system. If Nessus finds any weaknesses, like outdated software or weak passwords, it compiles them into a report, which administrators can use to improve their system's security. It is especially valuable for continuous security monitoring, vulnerability risk assessment, and compliance auditing. Nessus is known for its comprehensive vulnerability database and regular updates, which keep it equipped to recognize the latest known vulnerabilities and compliance issues.
Range of functions
- Vulnerability Scanning: It scans systems, networks, and applications to identify known vulnerabilities, such as outdated software, missing patches, or misconfigurations.
- Compliance Checking: Nessus can assess if systems comply with various security standards and policies, like PCI DSS, HIPAA, or GDPR.
- Content Auditing: It can search for sensitive data, such as credit card numbers or social security numbers, that may be improperly stored.
- Host Discovery: Nessus can identify all the devices connected to a network, including servers, routers, switches, and virtual machines.
- Malware Detection: It scans for signs of malware infections on a system.
- Web Application Scanning: Nessus can test web applications for vulnerabilities such as SQL injection, cross-site scripting (XSS), and other web-based threats.
- Configuration Auditing: The tool can check systems against configuration best practices to ensure they are set up securely.
- Network Scanning: Nessus can scan a range of IP addresses to identify all the services, open ports, and protocols being used on the network.
- Mobile Device Scanning: It can also scan mobile devices for vulnerabilities.
- Report Generation: After completing scans, Nessus generates detailed reports that outline discovered vulnerabilities and provide guidance on how to remediate them.
- Customization: Users can create custom scan policies and plugins to tailor the scanning process to their specific needs.
User-friendliness
- Graphical User Interface (GUI): Nessus provides a clean and intuitive web-based interface, making it accessible for users who may not be comfortable with command-line tools.
- Templates and Policies: Nessus offers pre-defined templates and policies for various types of scans, which simplifies the process of setting up and running assessments.
- Detailed Reports: The reports generated by Nessus are detailed yet clear, with color-coded risk factors and recommendations for remediation, which are helpful for both technical and non-technical users.
- Plug-and-Play Functionality: For many standard scans, Nessus works with minimal configuration out of the box, allowing users to begin scanning with just a few clicks.
- Customizable Scans: For more advanced users, Nessus allows the creation of customized scans, which can be as simple or as complex as the user is comfortable with.
- Tutorials and Support: There is a wealth of documentation, tutorials, and community support available for Nessus, which can help new users get up to speed quickly.
- Integration Capabilities: Nessus can integrate with other systems and security tools, offering flexibility and ease of use within a larger security infrastructure.
What Nessus is missing?
Nessus is not designed for real-time network monitoring or intrusion detection, meaning it won't keep watch over your network for active threats. It identifies vulnerabilities but doesn't fix them, so you still need to patch and secure your systems separately. Also, while it's great for identifying weaknesses, it doesn't offer advanced threat intelligence that some specialized tools provide. Additionally, if you're using the free version, you might find it limited in scope and capability compared to the paid versions. For businesses or users looking for more customization, Nessus might not allow as much flexibility as open-source tools where you can write your own scripts or plugins. Nessus serves as a diagnostic tool within a broader security framework, functioning to scan and identify potential vulnerabilities in computer systems. It's important to understand that Nessus itself doesn't block or prevent attacks; its role is to highlight weaknesses that could potentially be exploited by attackers. The responsibility for addressing and patching these vulnerabilities rests with the system administrators. Implementing the fixes based on Nessus's findings is a critical step toward fortifying the system's defenses.
“In theory... but is it ? Let's TEST it!”
Nessus in practice
Review
User-friendliness:
Installation and setup:- The installation is very simple. It just required download a simple Debian package and dpkg it.
- Afterwards you just start the Nessus service and it's ready to use.
- Tinkering with 1/2 tests already shows you the capabalities of Nessus. The pre-defined methods/checks for already existing and known vulnerabilities allows you to quickly install it and do a scan of your network or server.
- All the options are divided into their own submenus and each option is self-explanatory.
- As it's a commercial product, the documentation is easy to understand and categorized into sub-sections for each task.
- It also has several specific-scenario docs.
- Nessus provides a wealth of documentation, tutorials, and guides for common tasks, helping users to effectively utilize the tool.
- Nessus has a supportive community forum and customer support. The responsiveness and helpfulness of these resources are generally well-regarded, offering valuable assistance to users.
- Configuring scans in Nessus is relatively straightforward. The options are well-explained, making it accessible even for users who are not deeply technical.
- The performance is generally smooth and efficient, typically not causing significant system lag during its operations. Our VM didn't experience any hiccups and the CPU and RAM usage were well within their means.
- The software worked flawlessly and we didn't experience any bugs in it's use.
- Nessus offers a high degree of customization, which is one of its key strengths. Users can create custom scan policies and plugins, adapting the tool to their specific security requirements. This feature is particularly beneficial for businesses or individuals with unique network environments or specific security concerns. The tool allows for adjustments in the depth and breadth of scans, targeting specific areas of a network or system as needed.
- Nessus demonstrates excellent adaptability, catering effectively to both novice and advanced users. For beginners, it offers pre-defined templates and an intuitive interface, simplifying the scanning process. Advanced users benefit from its extensive customization options, enabling in-depth and tailored security analyses. This dual approach ensures that Nessus is accessible and valuable to a wide range of users with different skill levels and security needs.
- Nessus performs its tasks effectively, accomplishing its intended functions with a reasonable amount of user input. It efficiently identifies vulnerabilities and security issues, requiring minimal setup for standard scans, making it both user-friendly and proficient in its core capabilities.
- The time from launching Nessus to obtaining meaningful results is impressively swift. Users can quickly set up and initiate scans with it's generous pre-made templates, leading to prompt generation of detailed and actionable security reports. This efficiency is a significant advantage for timely vulnerability assessment.
- Nessus effectively communicates feedback and errors, providing constructive and clear guidance. It not only identifies issues but also offers recommendations for resolution, aiding users in addressing and mitigating identified vulnerabilities. This approach is particularly helpful in guiding users through the process of improving their system's security.
Security in Communications:
Encryption:- Testing Encryption in Communication: Even in the free version, Nessus supports encrypted communications with the target systems using SSL/TLS during the scanning process. You can verify this by checking the configuration settings and observing the network traffic during a scan.
- Encryption of Results: Nessus stores scan results securely and locally. You can review the documentation or settings to confirm if it encrypts the data at rest.
- Authentication Mechanisms: Nessus Essentials requires user authentication to access the application. This requires you to pre-register in their system and log in afterwards.
- Data in Transit: Nessus typically encrypts data transmitted between the tool and the systems being scanned, usually utilizing SSL/TLS encryption by default. This ensures the security of data during scans. Users can confirm the encryption through network monitoring tools to ensure the data in transit is protected.
- Data at Rest: Nessus incorporates measures to safeguard sensitive data, such as scan results and configurations, even in its free version. While the advanced data protection features might be more extensive in paid versions, the basic security provided for stored data in Nessus still maintains a level of integrity and confidentiality, ensuring that sensitive information remains secure.
Perfromance analysis:
Scan Efficiency:- The tests run for quite a while, but the results are immediately shown. It first scans for the surface information about the network/target and it's processes, ports and services. Afterwards it starts the vulnerability scan, which takes the most time.
- The impact on performance was neglibile. The CPU and RAM usage were well within their means.
- It provided very accurate information about the target and when testing the Metasploitable VM, it showed a lot of vulnerabilities which we could then exploit and test other frameworks.
Conclusions
After thoroughly testing Nessus, I've found it to be a robust and efficient solution for identifying vulnerabilities within network systems. The tool's ability to run over 1200 checks on a computer makes it an indispensable asset for pinpointing a wide range of potential security issues, from outdated software to weak passwords.
The range of functions offered by Nessus is impressive. It adeptly handles tasks like vulnerability scanning, compliance checking, content auditing, and more. The tool's capacity for host discovery and malware detection is particularly noteworthy, offering a comprehensive view of network security.
From a user-friendliness perspective, Nessus excels with its intuitive web-based interface. This feature makes it accessible even to those not comfortable with command-line tools. The availability of pre-defined templates and policies streamlines the process of setting up scans, a plus for users at all skill levels.
One of the few drawbacks I've noticed is that Nessus is not designed for real-time network monitoring or intrusion detection. This means it can't actively watch over your network for ongoing threats, which is a limitation in certain scenarios. Also it's limited only to the local network as it can't access and evaluate external servers/hosts.
In practice, Nessus performs exceptionally well. The tool efficiently scans networks, providing detailed reports that are both comprehensive and easy to understand. These reports offer valuable insights and recommendations for remediation, crucial for enhancing network security.
In summary, Nessus is a powerful tool for vulnerability assessment, offering an extensive range of features and an intuitive user interface. While it does have some limitations, such as the lack of real-time monitoring capabilities and external network tests, its strengths in scanning and reporting make it an essential tool for network security management.