Why zombie APIs are a ticking time bomb for your business

In this series, we look at the security challenges and opportunities facing application programming interfaces (APIs). This article considers zombie APIs, while companion pieces will look at the security potential of session identifiers and how to navigate the release cycle for APIs.

The silent threat of zombie APIs

In today's interconnected world, APIs are the backbone of modern software. They enable applications to communicate with each other and share data seamlessly, powering everything from mobile applications to complex enterprise systems.

While we often focus on the security of active, well-maintained APIs, a silent threat lurks in the shadows: zombie APIs. These are the forgotten, outdated, and often undocumented APIs, and they pose a significant security risk, acting as hidden entry points for attackers and jeopardizing your entire digital ecosystem.

What are zombie APIs?

Zombie APIs are APIs that are no longer actively used, maintained, or properly documented, yet remain functional (or partially functional) and accessible. They're like forgotten servers or abandoned applications — still running, but neglected and vulnerable. These digital ghosts can arise for various reasons:

• Deprecation without decommissioning: Features are often deprecated, but the corresponding APIs are left running, creating a breeding ground for vulnerabilities.
• Lack of API lifecycle management: Without a clear process for retiring APIs, they can linger long after their usefulness has expired.
• Shadow IT: Developers may create APIs for specific projects without proper authorization or documentation, leading to orphaned APIs.
• Mergers and acquisitions: Integrating systems from different companies can result in a graveyard of forgotten APIs from acquired entities.
• Poor documentation: Even if an API isn't intentionally abandoned, inadequate documentation can make it difficult to understand its purpose or status, effectively turning it into a zombie.

The perils of the undead

Zombie APIs present a multitude of security risks:

• Vulnerability hotspots: Lacking maintenance and security patches, zombie APIs become easy targets for attackers. Known vulnerabilities remain unaddressed, creating gaps in defenses.
• Data breaches: Exploiting vulnerabilities in zombie APIs can grant attackers access to sensitive data, leading to costly data breaches and reputational damage.
• Compliance nightmares: Outdated APIs are unlikely to meet current security and compliance standards, exposing organizations to potential fines and legal repercussions.
• Operational disruption: A compromised zombie API can disrupt business operations, impacting critical services and customer experience.
• Amplified attack surface: Every active (and especially inactive) API expands your attack surface. Zombie APIs significantly increase this surface, providing more opportunities for malicious actors.

Bringing APIs back to life

The key to mitigating the risks of zombie APIs lies in proactive API management:

1. API discovery:

Regularly scan your environment to identify all APIs, including those that may be forgotten or undocumented. Automated tools can help with this process.

2. Robust API lifecycle management:

Implement a clear and comprehensive lifecycle for your APIs, from design and development to deployment, maintenance, and eventual retirement.

3. Proper API retirement:

When an API is no longer needed, retire it properly. This involves a structured process. Here's a breakdown with examples:

• Notification: Inform users about the API's deprecation and provide migration guidance.

• Deprecation period: Allow sufficient time for users to transition to a new system before fully retiring the API. It’s worth adding a ‘sunset’ header to an HTTP to proactively tell clients that a resource is going to become unavailable at a specific point in the future.

• Documentation updates: Clearly mark the API as deprecated in your documentation.

• Traffic redirection (if applicable): Redirect traffic to a replacement API if one exists.

• Decommissioning: Remove the API from your production environment. This involves removing the API code from servers, deleting any associated databases or infrastructure components, and disabling any access controls or API keys associated with the decommissioned API.

• Monitoring: Monitor for any residual traffic or dependencies even after decommissioning.

4. Vulnerability scanning and penetration testing

Regularly scan all APIs, including those suspected of being zombies, for vulnerabilities. Penetration testing can help identify weaknesses that automated scans might miss.

5. API documentation is crucial

Maintain accurate and up-to-date documentation for all APIs. This includes their purpose, status and intended use.

6. Security best practices

Implement robust security practices for all APIs, including authentication, authorization, rate limiting, and input validation.

Conclusion

Zombie APIs are a silent but potent threat to your organization's security. Ignoring these digital ghosts can have severe consequences. By implementing a proactive approach to API management, including proper API retirement processes, you can minimize the risks and protect your business from the undead. Don't let your APIs become zombies — take control of their lifecycle and ensure they are either actively serving your needs or laid to rest securely.

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Note: This article was originally published on LinkedIn.