Zombie APIs: What They Are and Why You Should Care

One famous case of a major telecom player involved 10 million customer accounts being breached, and days later, an extortion demand for £1 million cash was also made. The weak link? A forgotten ‘Zombie API.’

This isn’t just a one-off case. As per DarkReading, U.S. companies potentially lost between $12-23 billion just in 2022 from API-related security breaches. As APIs continue to rise across the business landscape, powering digital infrastructure, they unknowingly breed new vulnerabilities.

In this post, we will cover Zombie APIs—what they are and why you should be worried about them—and then discuss how to avoid having your organization become the next API security breach headline. So, let’s dive in.

What are Zombie APIs?

Although they are not creepy monsters from a horror movie, the existence of Zombie APIs in API management is still true. Dead, obsolete, or otherwise unsupported APIs still exist within an organization’s IT infrastructure, of which the development and operations teams are often unaware.

A Zombie API is an application programming interface that remains available for use, but the organization no longer monitors, updates, or officially supports it. Project changes, staff turnover, or oversight during system updates are the likely reasons that lead to Zombie APIs.

The situation is alarming when it comes to zombie APIs. Since these APIs do not have regular support, they attract hackers and pose a major risk to an organization’s security by allowing access to sensitive data or critical systems.

Scenarios Zombie APIs often show up in a few scenarios:

• Deprecated APIs that were not sufficiently sunset
• Dead APIs for finished projects
• Production environments running test or dev APIs by mistake
• Service Level Agreements (SLA) APIs of acquired companies that are not fused or retired

Risks Associated with Zombie APIs

Having Zombie APIs in your organization is like having a back door for hackers to enter. Let’s explore the risks associated with them:

Security Vulnerabilities: 

Zombie APIs are mostly old versions of APIs where the security patches and upgrades are overlooked. In simpler terms, they often have low-hanging fruit for attackers looking to leverage known vulnerabilities enabling unauthorized access into your systems. 

Such APIs may also have deprecated authentication methods or weak encryption, which can lead to a higher level of compromise of the company’s network.

Sensitive Information Leakage: 

Although dormant, Zombie APIs may still access sensitive data (or Personally Identifiable Information in some cases). Data breaches that stem from compromising these APIs are potentially disastrous and can, unfortunately, result in customer information leaks, financial data loss, or sensitive business intelligence leaking out.

Maintenance Challenges: 

Since Zombie APIs are retired, any team may not actively maintain them. They can present a huge technical debt. Even worse, they might be using old libraries or frameworks with the potential to break compatibility and grow the overall system architecture’s inherent complexity. 

This can slow down the development process, and updating later on will be more difficult and challenging.

Reputation Damage: 

If a Zombie API is breached, it can spell big trouble. It can cause immediate costs directly from incident response and system recovery, but it can also potentially lead to loss of tens of thousands or millions in fines due to non-compliance with data protection regulations.

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• We’re the only company that combines automated & manual pentest to create a one-of-a-kind pentest platform.
• Vetted scans ensure zero false positives.
• Our intelligent vulnerability scanner emulates hacker behavior & evolves with every pentest.
• Astra’s scanner helps you shift left by integrating with your CI/CD.
• Our platform helps you uncover, manage & fix vulnerabilities in one place.
• Trusted by the brands you trust like Agora, Spicejet, Muthoot, Dream11, etc.

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How to Prevent Zombie API Exposure

By adopting best practices and using appropriate tools, you can do a lot to avoid the Zombie APIs in your systems. Here’s how:

• Create Positive API Principles: Create an explicit outline of the policies that should be maintained during each phase of your API’s lifecycle. It should contain rules for API creation, documentation, maintenance, and retirement. Establish a formal API decommissioning process so that the old APIs are not left open for exploitation.

• Create API Inventory: Keep a complete record of all APIs in your environment. Maintain metadata like API owners, purpose, access levels, and status centralized inside the repository. Perform regular audits of this inventory to flag unused or obsolete APIs that might require some action (or retirement).

• Automate API Management: Use automated API discovery tools that support automated discovery, monitoring, and analysis. These tools will help you identify Zombie APIs by pointing out inactive ones along with usage patterns so that they can be caught before any threat actor exploits them.

• Build/Maintain a Third Party API Catalogue: Record all 3rd Party APIs your systems interact with. Keep this catalog up to date, and you should review it periodically to verify that these third-party APIs are still supported and secure. Have a plan to replace or remove an API if that third-party API becomes redundant or vulnerable.

• Ensure Developer Awareness: Train your engineering team (not just development) on API security best practices, including Zombie APIs and their risks. Develop a security-aware culture and get your developers to be more proactive in ensuring that they document APIs correctly, maintain them thoroughly, and decommission them as part of their regular work.

• Conduct Regular Security Testing: Regularly assess your APIs in the security context. This includes penetration testing, vulnerability scanning, and API-specific security testing. Regular testing can find Zombie APIs and other security risks associated with APIs in general before they are the next target.

How to Detect Zombie APIs?

Zombie APIs happen, no matter how strong your prevention processes are. Keeping an API ecosystem safe is impossible without catching exposed dormant threats. Below are some easy-to-use tools to identify Zombie APIs in your business.

Astra Pentest: Detailed security testing of all APIs

Astra Security provides a specialized API security testing service that takes a comprehensive approach to discovering Zombie APIs. Manually test and run automated scans using expert team member(s) to evaluate your API ecosystem from top to bottom. Astra Pentest can detect all vulnerable APIs that you might have overlooked.

It not only can help you find Zombie APIs but also perform thorough pentests and provide detailed reports with details of the risks and suggestions for remediation actions. 

Free Tools

Although professional & enterprise solutions like Astra Pentest provide the best detection, there are also some free tools that you can use to search for possible Zombie APIs:

• ZAP ( Zed Attack Proxy): ZAP is an open-source security testing tool that helps you perform security testing on APIs and find Zombie APIs. It does this by crawling your applications and identifying potential entry points.

• Postman – API development: Particularly successful at generating alarms on how APIs are used in practice, tracking response times that identify unused or broken ones.

These open-source tools may not be as complete or robust as professional services, but they provide a foundation for smaller organizations and are great supplemental solutions in any API security plan.

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

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Final Thoughts

Zombie APIs may not seem like something to worry about, but they can be a real pain if left unmanaged. Like a set of digital keys you’ve hidden under the doormat, they’re fine until someone with bad intentions comes by and picks them up.

APIs also have the potential to become digital zombies, and staying in control of your API inventory and continual testing for security risks is a large part of preventing Zombie APIs. They simply have no place when it comes to securing production workloads. 

Finding and securing deprecated or old APIs may not be convenient, but it’s much better than being affected by a security breach. As we know from the API security world, what you don’t know can hurt you. Therefore, be proactive about handling such cases properly and make the best use of the tools and security experts available. Need help securing your APIs? Astra’s here to help.

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