Open-Source Software Security: A Complete Guide

Open-source software has become an integral part of modern software development. For example, over 93% of developers use Git, the open-source version control system to build and deploy software. However, this widespread adoption also introduces significant security risks. According to data from GitHub's Security Advisory database, an average of 11 malicious NPM packages are being reported on a weekly basis in 2024.

As companies continue to rely on open-source software to meet their software development needs, ensuring its security is important. Understanding open-source software security is essential for protecting against vulnerabilities, preventing data breaches, and maintaining compliance with regulatory requirements. 

In this comprehensive guide, we will cover everything you need to know about open-source software security and highlight key strategies for its implementation.

What is Open-Source Software?

Open-source software (OSS) refers to software that is released under a license that allows users to use, inspect, study, change, and distribute the software and its source code. It is developed collaboratively and is often available for free. 

Companies frequently integrate open-source code into their applications in various ways. Developers may import open-source packages or plugins into their software to leverage these components' functionality. For instance, an open-source package in Python can add specific capabilities to an application without the need to develop that functionality from scratch. Organizations can also deploy standalone open-source components, such as Kubernetes, to host applications or Jenkins as part of their continuous integration and continuous development (CI/CD) pipeline.

Organizations utilize OSS to cut costs and speed up the software development process. By integrating pre-existing code, developers can shorten their time to market and quickly add the features that their customers value most.

What is Open-Source Software Security?

Open-source software security involves identifying, mitigating, and preventing vulnerabilities, threats, and risks associated with using open-source components in software development. 

Any security risks or vulnerabilities in the open-source software that companies use can significantly impact them if not identified and remediated before attackers exploit them. For example, an insecure release in an open-source component like Jenkins could create a backdoor into a company's CI/CD pipeline. Or a hacker could exploit a vulnerable open-source Python package to compromise an application that relies on it.

Because the source code is available for free, security vulnerabilities in open-source software have the potential to spread rapidly across many businesses. 

Companies can protect their data, systems, and reputation by implementing effective open-source software security practices. These practices also help mitigate a security breach's financial and legal risks, ensuring a more secure software development and deployment environment.

What are Some Risks Associated With Open-Source Software?

OSS's transparency and collaborative nature drive innovation and introduce unique security challenges and risks. These risks include:

1. Public Domain Vulnerabilities

Open-source code is accessible to anyone, including potential attackers who can scrutinize it for vulnerabilities. This accessibility means attackers can exploit weaknesses found in open-source code to breach an organization’s systems and data.

2. Supply Chain Risks  

OSS components are widely used across numerous projects and systems, making vulnerabilities in these components potentially devastating to the entire software supply chain. An example is the Log4Shell vulnerability in Apache Log4j, which allowed attackers to execute code remotely and impacted countless applications globally.

3. Licensing and Intellectual Property Risks

Using OSS comes with legal responsibilities tied to the software's licenses. Each open-source license has specific terms and conditions regarding the software's use, modification, and distribution. Failing to comply with these licenses can lead to legal disputes, financial penalties, and damage to your reputation.

4. Inadequate Maintenance and Support

While some OSS projects benefit from robust community support and regular updates, others may suffer from inadequate maintenance. Projects that are no longer actively maintained can leave users with outdated and vulnerable code and pose significant security risks. The Shellshock vulnerability in Bash, which was unpatched for years, is a notable example of the dangers of inadequate maintenance. 

5. Community and Contributor Risks

The open nature of OSS means that anyone can contribute, which can be a double-edged sword. While the collaborative nature of open source can drive innovation and rapid development, not all contributors may adhere to security best practices. This can introduce risks such as poorly written code, unintentional vulnerabilities, or even malicious contributions. An example is the event-stream incident, where a widely used Node.js package was compromised by a malicious contributor, leading to potential security breaches in applications using the package. 

How to Implement an Open-Source Security Strategy   

Ensuring the security of OSS is a crucial priority for developers and organizations relying on these powerful tools. In our experience, an effective OSS security strategy is built on these crucial steps.

1. Run Software Composition Analysis on Your Codebase to Automatically Detect Vulnerabilities 

You can't secure what you don't know you have. Knowing exactly what open-source components you rely on is crucial for identifying vulnerabilities and managing risk. Use a Software Composition Analysis (SCA) tool like OWASP Dependency-Check or Codacy’s SCA to scan your codebase and identify dependencies and known vulnerabilities automatically. Better yet, integrate it into your CI/CD pipeline to continuously scan your codebase for open-source components and their vulnerabilities.

Example:

✗ High severity vulnerability found in axios@0.21.1
  Description: Regular Expression Denial of Service (ReDoS)
  Info: (link unavailable)
  Upgrade to axios@^0.21.2 to fix

You can set your software release policies to fail builds if high-risk vulnerabilities are detected, ensuring issues are addressed before deployment.

2. Maintain a Software Bill of Materials (SBOM) That Lists All Open-Source Components in Your Project

Leveraging your SCA tool, maintain a Software Bill of Materials (SBOM) that lists all open-source components in your project, including versions and license information. SBOM systems inventory code subcomponents, allowing your security team to identify code with known vulnerabilities. When a critical vulnerability is found, the developers can reference SBOM artifacts and determine if there is an impact on the code. To generate a standardized SBOM, you can use the SPDX (Software Package Data Exchange) format, as shown below.

Example: SPDX SBOM file snippet

{
  "name": "My Project",
  "version": "1.0",
  "components": [
    {
      "name": "axios",
      "version": "0.21.1",
      "license": "MIT"
    },
    {
      "name": "express",
      "version": "4.17.1",
      "license": "MIT"
    }
  ]
}

3. Assess the Design

When considering an open-source component, think like a designer. Ask yourself: "If I were to build this from scratch, what security features would I include?" This mindset helps uncover potential gaps in the existing design. Even if you can't modify the source code directly, consider adjusting configurations or environments to enhance security. For instance, if an open-source package opens unnecessary ports or has modules you aren't using, disable them through system-level settings. Also, configure only HTTPS (SSL/TLS) for encrypted communication.

4. Research Community Security Practices

Investigate the security and support policies of the open-source community behind the software you're using. Are there regular security updates? Are the software releases cryptographically signed? How quickly are vulnerabilities patched? Understanding these aspects helps you gauge the reliability of the software and its community support. 

The Open Source Security Foundation (OpenSSF) Best Practices badge is a valuable indicator for open-source software projects that follow best practices. For example, Zap Proxy, a free, open-source tool that helps identify security vulnerabilities in web applications, displays the badge on its GitHub page.

5. Keep OSS Up-to-Date

Stale OSS libraries can lead to security vulnerabilities. Regularly update your OSS components to ensure you have the latest security patches and features. Use automated tools like GitHub Dependabot to automatically create pull requests for updating outdated dependencies.

6. Govern Your Open-Source Usage

Establish clear and well-documented guidelines on open-source usage within your organization. This should cover approval processes, security considerations, and contribution policies. Ensure your organization adheres to licensing requirements, understands the implications of using different open-source licenses, and maintains proper documentation. Remember, nothing kills innovation faster than a lawsuit.

7. Implement Security Testing

Even if an open-source component is secure, security vulnerabilities can arise from improper use of open-source libraries. For example, failing to sanitize input using a database query engine can lead to vulnerabilities like SQL injection.

To mitigate this, implement a robust security testing strategy:

• Static Application Security Testing (SAST): SAST tools can help identify potential vulnerabilities in your codebase. These tools examine your source code directly and can detect issues such as SQL injection and Cross-Site Scripting (XSS).
• Dynamic Application Security Testing (DAST):  DAST tools analyze your application's runtime behavior. They can detect vulnerabilities like input validation flaws, authentication weaknesses, and session management issues.

By integrating both SAST and DAST tools into your security strategy, you can ensure comprehensive coverage and protection against various vulnerabilities.

Automate Your Open-Source Security Strategy

Maintaining a secure software environment requires constant vigilance, especially when dealing with open-source components. Manually vetting libraries, conducting code reviews, and running security tests can be time-consuming and resource-intensive.

This is where Codacy comes in. Codacy's comprehensive suite of tools automates key aspects of your open-source security strategy, freeing you to focus on development and innovation.

Codacy's SCA continuously monitors your codebase for known vulnerabilities and risks in open-source libraries. This proactive approach ensures you're alerted to potential issues as soon as they arise. Also, Codacy's SAST functionality reviews your codebase to identify common application security weaknesses like those outlined in the OWASP Top 10.

By integrating Codacy into your development workflow, you can get ahead of your open-source software security. Take the first step toward securing your open-source software today with a Codacy free trial.