Continuous Integration and Continuous Delivery (CI/CD) security has become crucial to modern software development practices. As the speed of software development increases with DevOps and Agile methodologies, there is a growing need to ensure the integrity of software across the entire development pipeline.

CI/CD security encompasses the practices, tools, and methodologies that protect the software delivery pipeline from potential threats. In essence, it’s about ensuring that the code we’re integrating and deploying and the software comprising the pipeline itself is as secure as possible. This involves securing the development environment, the code repository, the build system, the deployment pipeline, and the software that’s being delivered.

The goal of CI/CD security is two-fold. First, it aims to prevent unauthorized access and potential tampering with the software during the development process. Second, it aims to ensure that the software that’s being delivered is free from vulnerabilities that could be exploited once it’s in the hands of the end-users.

How CI/CD Security Works

CI/CD security works by implementing security measures at every stage of the software development pipeline:

• Development: In the development environment, access controls and encryption are used to prevent unauthorized access and code tampering. The code repository is similarly protected, with measures such as two-factor authentication and automatic vulnerability scanning to ensure that the codebase remains secure.
• Build: The build system is another critical element in CI/CD security. Here, tools like static code analysis and software composition analysis are used to identify and fix potential security issues before the software is deployed. These tools check for common security vulnerabilities, such as SQL injection or cross-site scripting, and alert the development team so they can address the issues.
• Deployment: At this final stage, CI/CD security involves measures like automated deployment, which minimizes the risk of human error; dynamic testing, which simulates attacks against running applications in test environments; and continuous monitoring, which allows for rapid response to security incidents.

Notable Supply Chain Attacks and Lessons Learned

One of the main risks to the software delivery pipeline is supply chain attacks. Some of the early attacks include NotPetya and ASUS Live Update. Some more recent attacks further illustrate how neglecting CI/CD security can be catastrophic.

Microsoft Exchange Server

The Microsoft Exchange Server attack, which occurred in early 2021, is a stark reminder of the importance of robust CI/CD security. In this attack, a group of hackers exploited vulnerabilities in the Microsoft Exchange Server to gain access to thousands of servers worldwide. This was possible because the software was not sufficiently hardened before deployment, allowing attackers to exploit these vulnerabilities.

The lesson learned from this attack is the importance of thorough security testing and vulnerability scanning before deployment in the CI/CD pipeline. By identifying and fixing security vulnerabilities before software is deployed, companies can significantly reduce the risk of similar attacks.

SolarWinds

The SolarWinds attack, which took place in late 2020, was probably the largest and most severe global-scale supply chain attack. Attackers were able to infiltrate SolarWinds’ development environment and insert malicious code into the company’s software update system. This enabled them to distribute their malware to thousands of SolarWinds’ customers, which included US government agencies and a majority of Fortune 500 companies.

This attack highlighted the critical importance of securing the development environment and the code repository. Additionally, the attack underscores the importance of robust access controls and monitoring systems to detect unauthorized activity in these systems.

How Can CI/CD Security Measures Prevent Supply Chain Attacks?

Supply chain attacks are insidious because they exploit the trust that organizations place in their suppliers and vendors. Implementing strong CI/CD security measures is vital for preventing such attacks. Here’s how basic CI/CD security measures can go a long way towards preventing the next attack:

• Integrity checks: By enforcing integrity checks at every step, from code submission to deployment, organizations can ensure that the code has not been tampered with. Techniques such as code signing ensure that only legitimate code is integrated into the system.
• Automated vulnerability scans: CI/CD pipelines can automatically scan for vulnerabilities in both the application code and its dependencies. If a vulnerability is detected, the pipeline can halt the deployment, ensuring that potentially compromised code doesn’t get to production.
• Immutable infrastructure: By adopting an immutable infrastructure approach, where infrastructure components are replaced rather than changed, organizations can ensure a consistent and secure deployment environment, making it difficult for attackers to make persistent changes.
• Limiting access: By adopting a principle of least privilege, where developers and operators only have the permissions they need, the risk of a malicious actor gaining broad access to the CI/CD pipeline is significantly reduced.
• Segmentation: By segmenting the CI/CD pipeline – ensuring development, testing, and production environments are separate and isolated – any compromise in one section is less likely to affect others.
• Patch management: An up-to-date CI/CD toolchain is vital. Regularly updating and patching CI/CD tools and infrastructure ensures known vulnerabilities are addressed, reducing potential attack vectors.
• Incident response plan: Having a clear incident response plan in place ensures that if a breach or vulnerability is detected, it can be quickly contained and addressed, minimizing potential damage.
• Education and training: Ensuring that developers, operators, and other staff are educated about the latest security threats and best practices can help prevent inadvertent breaches and reinforce the importance of security in the CI/CD process.
• Multi-factor Authentication (MFA): Requiring MFA for all access points to the CI/CD pipeline makes it harder for attackers to gain unauthorized access.

Advanced CI/CD security Best Practices

Now that we’ve reviewed basic security measures and how they can prevent supply chain and other attacks, let’s cover some more advanced CI/CD security best practices that can help you gain the edge over sophisticated attackers.

Binary Authorization

Binary authorization ensures that only trusted and verified code gets deployed in your production environment.

Implementing binary authorization involves creating and enforcing policies that dictate which binaries can be deployed in your environment. These policies should be based on various parameters, such as the origin of the binary, its compliance with certain security checks, and its approval status.

CI/CD Threat Modelling

Threat modeling is the process of identifying, understanding, and mitigating potential security threats in a system. Here are a few steps you can take to perform threat modeling for your CI/CD environment:

1. Understand the architecture of your CI/CD pipeline: This includes mapping out all the components and their interactions, identifying the assets, and understanding the data flows.
2. Identify potential threats to your pipeline: This could include unauthorized access, data leakage, code tampering, or any other security threats. Once you have identified these threats, you should assess their potential impact and likelihood of occurrence.
3. Design strategies to mitigate the threats: This could involve implementing additional security controls, modifying the architecture of your pipeline, or adopting new security practices.

Securing the Runtime Environment

The security of your runtime environment is equally important as the security of your CI/CD pipeline. A compromised runtime environment can lead to serious security breaches, including data leakage, unauthorized access, and service disruption.

Securing your runtime environment involves several practices:

• Regularly update the runtime environment: This includes updating the operating system, the runtime and orchestration platforms (like Docker or Kubernetes), and any other components used in your environment.
• Restrict privileges in your runtime environment: Limit the actions that can be performed in your environment and only grant necessary permissions. By doing so, even if an attacker manages to gain access to your environment, they will be limited in what they can do.
• Isolate runtime environments: Run each application or service in its own isolated environment, which will prevent any potential security threats from spreading across your system.

Continuous Dependency Scanning

Dependencies are a common vector threat vector in CI/CD pipelines. A single vulnerable dependency can compromise an entire system. Therefore, it’s crucial to continuously scan your dependencies for vulnerabilities.

Continuous dependency scanning involves integrating tools into your CI/CD pipeline that can scan the codebase, container images, and any other components used in the pipeline. Additionally, you should also monitor dependencies for changes. This could include new versions, updates, or patches, alerting you to potential security threats.

Secrets Management

Secrets, such as API keys, passwords, and tokens, are often used in CI/CD pipelines. However, if these secrets are leaked or stolen, they can be used to gain unauthorized access to your system. Therefore, it’s crucial to manage and protect your secrets properly.

Secrets management involves securely storing, accessing, and using your secrets. This typically involves using a secure vault to store your secrets, encrypting your secrets both at rest and in transit, and using secure methods to access your secrets. Moreover, regularly changing your secrets is crucial to prevent unauthorized access. By doing so, even if an attacker manages to steal your secret, they won’t be able to use it for long.

Conclusion

Securing the CI/CD pipeline is an essential aspect of modern software development. The software delivery pipeline is rife with potential vulnerabilities, from the codebase to the deployment stage. With the rise in devastating software supply chain attacks, CI/CD security serves as a critical line of defense.

To properly defend your CI/CD environment, multiple layers of security measures should be applied at each stage of the development pipeline. Access control mechanisms, automated vulnerability scans, and encryption are critical to securing the codebase and development environment. In the build and deployment phases, employing tools for static and dynamic code analysis, as well as implementing immutable infrastructure, can significantly mitigate the risk of security breaches.

Advanced practices such as CI/CD threat modeling, continuous dependency scanning, secret management, and dynamic environment hardening offer additional resilience against sophisticated attacks.

The risks are high, but effective tools and methodologies are available to mitigate them. With diligent implementation and ongoing vigilance, organizations can secure their CI/CD pipelines and their business integrity against evolving threats.