Safeguarding companies from cyber threats: best free cybersecurity open-source solutions

Companies now face an average of 1,308 cyberattacks each week—up 28% since late 2023. This rapid escalation highlights just how crucial robust cybersecurity has become, regardless of a company’s size.

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As cyberattacks continue to grow more frequent and sophisticated, businesses of all sizes are facing increasing risks. In 2024, the global cost of cybercrime is set to soar to $9.5 trillion USD, a sharp rise from $8 trillion just a year earlier. With damages from cybercrime projected to increase by 15% annually, it could reach $10.5 trillion by 2025. 

The past year has seen a sharp rise in attacks, with ransomware being particularly pervasive, accounting for nearly 70% of all detected incidents, according to Statista. In 2024, Microsoft reported that its customers faced up to 600 million cyberattacks daily, showing the increasing complexity of the digital threat landscape. These figures underscore the sophistication of today’s cybercriminals and the growing vulnerability of businesses and individuals to risks like data breaches, malware, and phishing. The adoption of cloud services and remote work models has further widened the attack surface, exposing security gaps across sectors like healthcare and finance. 

Small and medium-sized businesses (SMEs) are especially at risk. Cybercriminals often see them as easier targets compared to larger corporations, and the financial consequences for SMEs can be devastating. IBM’s research found that the average cost of a data breach reached $4.45 million in 2023, rising to $4.9 million in 2024. For many smaller businesses, a successful breach could be catastrophic, with some even forced to shut down. Alarmingly, 39% of SMEs have lost customer data due to breaches, eroding both customer trust and their hard-earned reputations. 

Adopting a proactive cybersecurity strategy is one of the most effective ways for businesses to reduce the risks posed by today’s increasingly hostile digital landscape. Protecting sensitive data goes beyond mere security measures—it’s about building customer trust, securing daily operations, and ensuring the company’s long-term future. Whether you’re leading a small startup or a large enterprise, investing in cybersecurity today is crucial to protecting your business tomorrow.  

Best free Open-Source solutions for SMEs  

Because these types of cyberattacks could easily happen to your business, it’s crucial to be prepared. We have searched for best free, open-source tools available to help organisations strengthen their cybersecurity measures without incurring in high costs. Here are some of the best options:  

1. DefectDojo

Purpose: Vulnerability management.  

Advantages:  

• Allows you to centralize vulnerability management from different scanning tools in a single panel.  

• Facilitates vulnerability tracking and generates detailed reports.  

• Allows integration with other security tools such as OWASP ZAP and Burp Suite.  

Disadvantages:  

• Requires a certain learning curve for customization and proper configuration.  

• Not as robust in terms of automatic integration with some systems.  

Website: https://www.defectdojo.org  

2. OpenVAS (Greenbone Vulnerability Management) 

Purpose: Vulnerability scanning.  

Advantages:  

• It is one of the most complete vulnerability scanners, with a large updated database of vulnerabilities.  

• Allows you to identify security flaws in networks and systems.  

• Easy integration with other security systems.  

Disadvantages:  

• Can generate false positives, requiring extensive manual validation.  

• Heavy scans that require considerable resources (CPU/RAM) on large networks.  

Website: https://www.greenbone.net/en/community-edition  

3. Nikto

Purpose: Vulnerability scanning on web servers.  

Advantages:  

• Quick to detect insecure configurations, outdated versions, and vulnerabilities in web servers.  

• Simple to use and has an extensive database.  

Disadvantages:  

• Not as effective at detecting modern vulnerabilities and does not have support for more advanced applications such as OWASP ZAP or Burp Suite.  

• Lacks deep dynamic analysis and has limitations compared to commercial scanners.  

Website: https://cirt.net/Nikto2  

4. OWASP ZAP (Zed Attack Proxy) 

Purpose: Dynamic web application security testing.  

Advantages:  

• Leading web application penetration testing tool.  

• It offers both active and passive vulnerability scanning.  

• It has a large user community and offers constant updates, as well as being easy to integrate with CI/CD pipelines. 

Disadvantages:  

• It requires advanced knowledge to take advantage of all its capabilities.  

• Its analysis can be slow in very large applications.  

Website: https://www.zaproxy.org  

5. Nmap 

Purpose: Port and service scanning.  

Advantages:  

• It is a versatile and robust tool for discovering hosts and services on the network.  

• It can be used for network discovery, security auditing, system detection, and vulnerability verification.  

• It supports NSE (Nmap Scripting Engine) scripts to add additional capabilities.  

Disadvantages:  

• It is not specific to vulnerabilities; it is more of a reconnaissance tool.  

• Scans can be easily detected and blocked by defence systems.  

Website: https://nmap.org  

6. Wapiti 

Purpose: Scanning web applications.  

Advantages:  

• Allows the discovery of vulnerabilities in web applications through “black-box” testing (without access to the code).  

• Compatible with numerous programming languages ​​and web frameworks.  

Disadvantages:  

• Does not have a graphical interface, which may make it less intuitive for some users.  

• Not as well-known or robust as OWASP ZAP in terms of detecting advanced vulnerabilities.  

Website: https://wapiti.sourceforge.io  

7. Lynis 

Purpose: Security auditing and vulnerability scanning in operating systems.  

Advantages:  

• Specialized in auditing Linux and Unix servers.  

• Offers a comprehensive assessment of system configurations, including services, files, and permissions.  

• Lightweight and fast in execution.  

Disadvantages:  

• Only designed for Unix-like systems, which limits its level of heterogeneity in Windows environments.  

• Not as efficient for detecting web vulnerabilities.  

Website: https://cisofy.com/lynis/  

8. ClamAV

Purpose: Malware detection.  

Advantages:  

• It is the most well-known open-source malware detection software, with capabilities for both servers and workstations.  

• It is frequently updated with new malware signatures.  

• Supports multiple platforms.  

Disadvantages:  

• It is not as effective as other commercial malware detection solutions (e.g., in terms of heuristic analysis).  

• It does not include advanced behavioural analysis capabilities.  

Website: https://www.clamav.net  

9. Rclone + Imapsync (for backups) 

Purpose: File backup and synchronization.  

Advantages:  

• Rclone supports multiple cloud storage providers (Google Drive, S3, Dropbox, etc.) and has great flexibility for backup automation.  

• Imapsync is an excellent tool for email synchronization between IMAP servers.  

Disadvantages:  

• Rclone may require advanced configuration for complex tasks.  

• Imapsync is limited to emails only and does not handle any other type of data.  

Website: https://rclone.org  

https://imapsync.lamiral.info  

10. Nuclei 

Purpose: Template-based vulnerability scanner.  

Advantages:  

• It is a lightweight and fast tool that allows you to run vulnerability scans using predefined templates.  

• It is very flexible and allows users to create their own templates.  

Disadvantages:  

• It requires scripting and templating skills to take full advantage of its potential.  

• It does not have a graphical interface and is purely CLI-based.  

Website: https://nuclei.projectdiscovery.io  

11. Schemathesis

Purpose: Security testing for REST and GraphQL APIs.  

Advantages:  

• Ideal for API security testing, including SQL and XXE injections.  

• Allows you to automatically create tests from OpenAPI specifications.  

Disadvantages:  

• It requires prior OpenAPI knowledge and advanced configurations.  

• It is not as robust for testing non-standard APIs such as REST or GraphQL.  

Website: https://schemathesis.io  

12. Faraday 

Purpose: Collaborative vulnerability management platform.  

Advantages:  

• Allows efficient integration between multiple security tools, centralizing test results on a collaborative platform.  

• Ideal for work teams, as it allows sharing and correlating information in real time.  

Disadvantages:  

• Can be complex to configure and manage.  

• Although the open-source version is functional, some advanced features are limited to the commercial version.  

Website: https://faradaysec.com   

13. Artemis 

Purpose: Vulnerability analysis and correlation to prioritize risks.  

Advantages:  

• Correlation of data from multiple security tools  

• Prioritization of critical vulnerabilities  

• Integration with multiple scanning tools  

• Intuitive interface  

Disadvantages:  

• Learning curve in configuration  

• Smaller community and less support  

• May have scalability issues in large environments  

Website: https://artemis.rapid7.com  

In our opinion, the most recommended are:  

• OWASP ZAP: For dynamic web security testing. If your focus is web application security, it is the most robust tool.  

• OpenVAS: For vulnerability scanning in systems and networks. It is the standard in open-source solutions for the detection of vulnerabilities in large infrastructures.  

• Nmap: Essential for network and service audits, ideal as a complementary tool.  

• Lynis: Crucial for internal auditing of Linux servers, improving the security configurations of the operating system.  
• DefectDojo: Centralizes and organizes vulnerability management, which is key if you work with multiple scanning tools.  

In conclusion, while open-source cybersecurity tools offer a cost-effective solution, it’s important to recognize that they require a different kind of investment—time and effort. When choosing open-source tools, it’s essential to remember that although they don’t come with a direct financial cost, you must invest time in learning how to use them and tailoring them to your business’s specific needs. These tools can be just as powerful as commercial alternatives, but the process of configuring and optimizing them can demand more time and expertise. 

Ultimately, prioritizing cybersecurity by leveraging these community-driven solutions can help organisations build strong defences and secure their digital assets. With the right tools and commitment, small businesses can protect themselves in today’s increasingly hostile cyber landscape.