Shadow APIs vs Zombie APIs – All You Need to Know

In the age of digital-first businesses, every other software solution either uses an API (Application Programming Interface) or makes one. They enable various applications and services to work together, enabling businesses to improve features, streamline user experience, and provide new exciting offerings. Unfortunately, the more APIs we collect and interact with, the more security challenges increase.

Shadow API vs Zombie API are two prominent API types that present substantial dangers for the enterprises that host them. While bearing some similarities, each of these hidden or forgotten APIs poses unique and significant risks that could endanger data security, system integrity, and regulatory compliance.

In this article, I will explain Shadow and Zombie APIs and their differences, along with the risks they bring to businesses. We will also discuss how to prevent Shadow API vs Zombie APIs and walk through some tools that can detect them and mitigate API security risks. So, let’s dig in.

What are Shadow APIs?

“Shadow API” – This term is self-explanatory; these are the APIs that were either not documented or unofficially developed within an organization where its IT infrastructure intended to implement and use them with any proper management.

Shadow APIs are generally born when developers develop hacky solutions to fulfill pressing project deadlines. In many cases, Shadow APIs are left undiscovered by IT and security teams – opening up an organization’s ecosystem to potential threats. Even if Shadow APIs fulfill the current development goals (most used for MVPs), they can result in severe exposure risk, especially when there is no discipline to keep them within bounds.

The following are major properties of Shadow APIs:

• No Official Documentation
• Not part of the organization’s API inventory.
• Frequently created by non-security-cleared techniques
• It may not go through a standard approval process.

What are Zombie APIs?

A zombie API is simply a deprecated, old, or abandoned API that is still operational and open up in the context of other systems where they have been functionally replaced despite having ceased being maintained by developers or maintainers.

Organizations unknowingly create zombie APIs when they miss the proper retirement or sunset of old APIs during system updates or migrations. This may happen because project handovers are not being properly done or the original developers are leaving without proper knowledge transition.

Essential Traits of Zombie APIs:

• Deprecated or not supported officially
• Set and forget application/website. 
• Little to no ongoing maintenance or security updates.
• Possibly vulnerable or out-of-date code configurations
• Rarely on the API inventory radar

Comparing Shadow APIs vs Zombie APIs

Understanding the similarities and differences between Shadow API vs Zombie API is crucial for effective API management and security. Let’s break down their key characteristics and use cases.

Key Similarities in Shadow and Zombie APIs

Critical Differences between Shadow and Zombie APis

How Shadow and Zombie APIs Come into Being?

It is possible to prevent and manage Zombie API and Shadow APIs right after knowing what situation your organization might be allowing them.

Scenarios Resulting in Shadow APIs:

• Rapid Prototyping – These are usually quickly built APIs to test new features.
• Fast-track Integrations: When projects that have an immediate need and are not able to go through the standard long approval process.
• Legacy System Bypasses: Designed to work with old/legacy systems and apps that do not have API support.

Scenarios Creating Zombie APIs:

• Abandoned Projects: APIs from terminated or abandoned projects that were not retired correctly.
• Legacy Partner Integrations: Old APIs still used by external partners but no longer maintained internally.
• System Migration APIs: The transitional APIs that should have been removed post-migration from one system to another.

Why Astra is the best in API Pentesting?

• We’re the only company that combines automated & manual pentest to create a one-of-a-kind pentest platform.
• Runs 120+ test cases based on industrial standards.
• Integrates with your CI/CD tools to help you establish DevSecOps.
• A dynamic vulnerability management dashboard to manage, monitor, and assess APIs your web app consumes.
• Conduct 2 rescans in 60 days to verify patches.
• Award publicly verifiable pentest certificates which you can share with your users.
• Helps you stay compliant with SOC2, ISO27001, PCI-DSS, HIPAA, etc.
• Trusted by the brands you trust like Agora, Spicejet, Muthoot, Dream11, etc.

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Risks Associated with Shadow & Zombie APIs

While Shadow API and Zombie API are different, they equally expose an organization to a great deal of risk. It is necessary to identify these risks for efficient API management and security. Let’s take a closer look at them:

• Security and Compliance Issues: Shadow and Zombie APIs often circumvent standard security policies and checks for regulatory or other forms of compliance. These APIs don’t usually have proper authentication, authorization, or encryption, which can break regulatory compliance, particularly in industries with strict and wide-ranging data protection rules like healthcare (HIPAA) or finance (PCI DSS).

• Maintenance and Documentation Challenges – Without proper documentation or wiki, it’s really hard for any developer (be it senior or junior) to understand the code/application. This absence of some official log means that crucial knowledge may drop into the void when the first developer exits.

• Data Leakage and Financial Loss: Both Zombie and Shadow APIs can become open doors for threat actors. Shadow APIs can unknowingly leak sensitive data, and Zombie APIs might come with vulnerabilities (for example, due to deprecated libraries) that a hacker could exploit. Such vulnerabilities lead to data breaches as well, which can lead to millions of dollars in GDPR fines or legal liabilities.

Best Practices for Managing Zombie and Shadow APIs

A balanced approach to proper management of shadow APIs and zombie APIs should consist of both technological means as well as organizational practices. Key strategies to manage the risks and secure APIs are as follows:

• Enforcing API Governance: Define rules and follow best practices around how APIs are created, stored, secured, and retired. For example, a set of standard approval processes for APIs, security requirements, and documentation standards should be followed by every developer while creating APIs in the organization.

• API Discovery and Inventory Management: Scan your whole ecosystem to find all APIs, not only the official ones but also Shadow & Zombie APIs. Keep all APIs, what they are for, who owns them, and their status up-to-date in an inventory to manage everything.

• API Lifecycle Management Automation: Use tools and procedures for API lifecycle to automatically manage the entire life cycle of APIs. This focuses on things such as versioning and deprecation signals to prevent the creation of Zombie APIs.

Tools for Detecting and Managing Shadow and Zombie APIs

Use specialized tools for effective management of Zombie and Shadow APIs. Some of them include:

Astra Pentest

Astra Pentest provides extensive API security testing for organizations. It makes it easy for organizations to find vulnerabilities that may live together within known and unknown APIs. Astra’s platform provides:

• 9,300 test cases for deep API security testing.
• Compliance checks for HIPAA, PCI-DSS, etc.
• Actionable remediation steps with details are available in the reports.
• Automatic security checks integrated into CI/CD pipelines.

Open Source Tools

• Akto: Left shift into continuous API security testing & inventory management.
• Metlo: Specializes in API discovery and custom rule writing for API testing.
• Swagger Inspector enables rapid testing and validation of APIs, which is useful for discovering undocumented endpoints.

Astra Pentest is built by the team of experts that helped secure Microsoft, Adobe, Facebook, and Buffer

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Final Thoughts

Despite the different ways Shadow APIs and Zombie APIs come into existence, they often have vulnerabilities in common that can significantly impact an organization’s security and compliance posture. To tackle these, we must take various steps, such as better API governance, regular discovery, asset inventory management, and continuous security testing.

The industry is becoming more complex, and companies must have strong countermeasures to fight against such APIs. If you are looking to improve the security posture of your APIs, take a look at how an integrated solution like Astra Pentest can help. Its capacity to spot Shadow API vs Zombie APIs, with detailed security assessments, makes it a very important player in your security toolkit.

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