Zombie APIs: Battling the Walking Dead in Your Software Stack

In the world of software development, APIs are vital conduits that enable applications to work harmoniously, exchange information, and ensure seamless functionality. However, not all APIs evolve gracefully; some become ‘Zombie APIs,’ quietly lingering in your system, posing unforeseen risks.

A Zombie API is an exposed API that has been left abandoned, forgotten, or 1outdated. Initially, these APIs served a specific function, but over time, that function is no longer necessary, or the API has been replaced or updated with a newer version.

The lack of proper management, version control, and deprecation procedures allows these APIs to linger, often unnoticed, and potentially pose risks to your software lifecycle. The term “zombie” aptly characterizes these APIs, as they continue to exist despite being outdated, much like the Walking Dead in horror movies. In the context of software development, understanding and addressing Zombie APIs is crucial to maintaining system security, efficiency, and overall health.

Read on to learn about exploring their lurking threats, why it is crucial to address them, and most importantly, how to address Zombie APIs in your software stack.

How to Detect Zombie APIs

Detecting Zombie APIs can be challenging, primarily because their existence often goes unnoticed until problems arise. To proactively identify these looming API remnants, consider the following approaches.

1. Regular API Audits: Conduct periodic audits, using penetration testing and vulnerability scans, of your API inventory. By reviewing your APIs systematically, you can identify outdated or unused APIs that might have turned into Zombie APIs.
2. User Activity Tracking: Keep records of user activities across all APIs. Monitoring user access patterns can help you identify which APIs are still in use and which have become redundant. Additionally, tracking IP addresses and assets received (such as tokens, cookies, or API keys) can provide valuable insights into API usage.
3. Code Analysis: Conduct thorough code reviews of your application’s source code. Look for any instances of API calls that are no longer used or necessary. Unused API calls can be a clear indicator of Zombie APIs hiding within your codebase.
4. Documentation Audits: Review your API documentation regularly. Ensure that it accurately represents the current state of your APIs. Outdated or misleading documentation can lead to confusion and make it difficult to identify Zombie APIs. Keeping your documentation up to date is crucial for maintaining a clear picture of your API landscape.

Why Zombie APIs Are a Threat

Zombie APIs, also known as deprecated or obsolete APIs, can haunt software development projects in many ways. Sometimes, older versions of APIs can be replaced by newer versions or even completely brand-new APIs. These APIs may lay dormant for existing customers consuming the API or it may be a simple oversight. Sometimes, APIs remain active when newer versions are made available or entirely new APIs have been introduced, creating confusion and inefficiency in the development process. In other cases, public HTTP endpoints are opened for testing purposes but are never appropriately closed, leaving vulnerabilities wide open. Regardless of why the public endpoints are left open, they represent a significant risk to your organization, and the products or services it offers, underscoring the importance of effectively managing and securing APIs to thwart potential threats.

We have explained why Zombie APIs pose a security risk if they are no longer receiving updates or patches, making them vulnerable to exploits and cyberattacks. By continuing to use these outdated interfaces, developers expose their applications and systems to potential breaches, data leaks, and other security threats. An API infiltration can expose sensitive customer data resulting in the loss of trust by your customers and your company’s reputation.

Lastly, Zombie APIs hinder innovation and hinder progress. They can limit a developer’s ability to take advantage of new technologies and features because they often lack support for modern functionalities. By eliminating these dormant APIs, developers can free up resources and focus on integrating more robust and up-to-date alternatives, accelerating software development, and enhancing the user experience. Ignoring Zombie APIs puts your company’s reputation and assets at risk, leaving your organization vulnerable to data loss, network lockouts, and other catastrophic consequences. Eliminating Zombie APIs is not only a security imperative but also a strategic move to ensure the longevity and competitiveness of software applications.

Check this out to learn more about API Penetration Testing. and OWASP Top API risks in 2023.

How to Kill a Zombie API

Managing and deprecating zombie APIs is critical for maintaining the security and efficiency of your systems. To ensure a smooth transition to new APIs and avoid potential disruptions, it is essential to follow best practices in communication, planning, and monitoring. Moreover, enhancing overall API security is vital to safeguard your organization and customers from vulnerabilities.

However, there are instances where organizations, like Twitter, have made abrupt changes to their APIs without prior notification. These sudden modifications can understandably cause disruptions and frustration among existing API consumers. To prevent such scenarios and gracefully deactivate a zombie API, consider the following approach:

1. Identify the Zombie API: Start by identifying which APIs are zombies. Analyze server logs, usage data, and API documentation to determine which APIs are no longer in active use.
2. Plan the Shutdown: Ensure that the zombie API is indeed no longer required by checking with the development team, product owners, or other stakeholders who may know the system’s history. Carefully plan the shutdown process, including creating a timeline and informing all relevant stakeholders. The schedule should allow for testing and validation to prevent unintended consequences.
3. Monitor the Shutdown: After shutting down the API, closely monitor the system to ensure there are no adverse effects. Review server logs, performance metrics, and relevant data to ensure the system continues to function properly.
4. Create a Replacement (if necessary): If clients rely on the API, create a replacement before fully deprecating it. This process can also help identify potential security risks and prevent future zombie APIs.
5. Intermittently Deactivate: Consider intermittently deactivating the API shortly before its full retirement to give users additional warnings and encourage them to switch to the new product.

Secure Your Organization’s APIs With BreachLock

Zombie APIs represent a burden on modern software systems, and addressing them is paramount to enhance security, reduce costs, and optimize overall performance. As software systems evolve and become more sophisticated, the meticulous process of spotting and removing zombie APIs becomes increasingly critical.

The process begins with identifying these dormant APIs, confirming their redundancy, carefully planning their shutdown, and vigilantly monitoring the system for any adverse effects. Organizations can significantly mitigate the risks associated with zombie APIs by following these essential steps.

BreachLock is a global leader in PTaaS (Penetration Testing as a Service) and penetration testing services. BreachLock offers automated, AI-powered, and human-delivered solutions in one integrated platform based on a standardized built-in framework that enables consistent and regular benchmarks of attack techniques, security controls, and processes. By creating a standardized framework, BreachLock can deliver enhanced predictability, consistency, and accurate results in real-time, every time.

Schedule a discovery call with one of our pentesting experts to discover how BreachLock’s PTaaS can help validate the security controls of APIs in your organization.