In the realm of mainframe security, we often focus on fortifying the “castle walls” – our firewalls, access controls, and intrusion detection systems. But what about the unseen threats lurking within the very software that powers our mainframes? In today’s interconnected world, the security of our systems hinges not just on internal defenses but also on the resilience of our software supply chain.

As a seasoned mainframe consultant with over 20 years of experience, I’ve witnessed firsthand the growing importance of software supply chain security (SSCS). Legacy systems, including mainframes, are not immune to vulnerabilities embedded within the software they rely on. These vulnerabilities can originate from open-source libraries, third-party vendor code, or even custom-developed components.

This blog delves into the critical aspects of SSCS for mainframe environments. We’ll explore the risks posed by software supply chain vulnerabilities, delve into key security practices like code signing and dependency management, and provide actionable steps to fortify your mainframe’s software ecosystem.

The Looming Threat: Software Supply Chain Vulnerabilities

Modern software development is a collaborative effort, with organizations leveraging a plethora of open-source libraries and third-party components to build complex applications. While this practice fosters innovation and efficiency, it also introduces inherent risks:

• Open Source Vulnerabilities: Open-source libraries offer numerous benefits, but they also come with potential vulnerabilities. These vulnerabilities can be introduced unintentionally during development or exploited by malicious actors who target popular open-source projects.
• Third-Party Code Risks: Similar to open-source libraries, third-party vendor code can harbor vulnerabilities. These vulnerabilities may go undetected for extended periods if proper security practices are not followed by the vendor.
• Hidden Backdoors: Malicious actors may attempt to inject backdoors into software during the development or distribution process. These backdoors can provide unauthorized access to your mainframe systems.

The Domino Effect: How Supply Chain Vulnerabilities Impact Mainframes

A seemingly insignificant vulnerability in a seemingly unrelated piece of software can have a devastating impact on your mainframe environment. Here’s how:

• Exploiting Dependencies: Attackers can exploit a vulnerability in a seemingly innocuous dependency to gain access to your mainframe system. This “supply chain attack” allows them to bypass traditional security measures focused on the mainframe itself.
• Zero-Day Attacks: New vulnerabilities (zero-day attacks) are discovered all the time. If a critical open-source library or vendor code harbors an undiscovered vulnerability, your mainframe could be at risk until a patch is available.
• Reputational Damage: A successful attack leveraging a software supply chain vulnerability can damage your organization’s reputation, leading to lost trust from customers and partners.

Building a Secure Software Supply Chain for Mainframes

Fortunately, several strategies can help you fortify your mainframe environment against software supply chain vulnerabilities:

• Code Signing: Code signing involves digitally signing software with a cryptographic certificate. This allows you to verify the authenticity and integrity of the code, ensuring it hasn’t been tampered with during distribution. Mainframe platforms like z/OS offer robust code signing capabilities to ensure the code you deploy originates from a trusted source.
• Dependency Management: Implementing a robust dependency management strategy is crucial. This involves:
  • Understanding Your Dependencies: Identify all the software components your mainframe applications rely on, including open-source libraries and third-party vendor code.
  • Vulnerability Scanning: Regularly scan your dependencies for known vulnerabilities. Utilize tools that integrate with your mainframe environment for seamless vulnerability assessment.
  • Dependency Updates: Stay updated on the latest security patches for your dependencies. Prioritize applying security patches for critical vulnerabilities promptly.
• Open Source Security Best Practices: When utilizing open-source libraries:
  • Choose Reputable Sources: Download software from well-maintained and trusted repositories with a strong track record of security.
  • Review Code: If possible, dedicate resources to review the source code of critical open-source libraries you rely on. This helps identify potential security issues.
• Vendor Due Diligence: Perform thorough security assessments of third-party vendors before integrating their software into your mainframe environment.
• Security Awareness Training: Educate your development teams about software supply chain security risks. This empowers them to make informed decisions regarding software selection and integration.
• Continuous Monitoring: Implement continuous monitoring solutions to detect suspicious activity within your software supply chain. This could involve monitoring for unauthorized code changes, unusual network traffic patterns, or anomalies in vendor code updates.
• Static Code Analysis (SCA): Utilize SCA tools to analyze the source code of open-source libraries and custom-developed components for potential vulnerabilities before deployment.
• Software Composition Analysis (SCA): Complement SCA with Software Composition Analysis (SCA) tools that identify known open-source vulnerabilities within your dependencies.

Collaboration is Key: Building a Secure Ecosystem

Software supply chain security is a shared responsibility. Here are some ways to foster collaboration for a more secure ecosystem:

• Engage with Open Source Communities: Contribute to open-source projects you rely on. This not only benefits your own security posture but also strengthens the overall security of the open-source community.
• Work with Vendors: Establish clear communication channels with your software vendors. Inquire about their security practices and encourage transparency in vulnerability disclosure.
• Industry Collaboration: Participate in industry-wide initiatives focused on software supply chain security. This allows you to share best practices and stay updated on the latest threats and mitigation strategies.

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Conclusion: Building a Fortress from Within

While robust firewalls and access controls are crucial, securing the software supply chain is equally important for a truly fortified mainframe environment. By implementing the strategies outlined in this blog, you can significantly reduce the risk of vulnerabilities lurking within your software ecosystem. Remember, software supply chain security is an ongoing process. Regularly evaluate your practices, stay informed about evolving threats, and adapt your strategies accordingly. By building a culture of security awareness and proactive risk mitigation, you can ensure your mainframes remain a reliable and secure platform for your critical business operations.

Additional Resources:

• Open Web Application Security Project (OWASP) – Software Supply Chain Security: https://owasp.org/www-project-kubernetes-top-ten/2022/en/src/K02-supply-chain-vulnerabilities
• National Institute of Standards and Technology (NIST) – Secure Software Development Framework: https://csrc.nist.gov/projects/ssdf
• Linux Foundation – Core Infrastructure Initiative (CII): https://www.linuxfoundation.org/