Effective Detection and Remediation of Shadow API and Zombie API

Itzik Alvas. Co-founder & CEO, Entro
March 11, 2024
API zombies

Welcome to the Matrix of API security, where not everything is as it seems. In one corner, we have the shadow APIs lurking unseen like digital ninjas at night. They move silently, hidden from the watchful eyes of your security protocols. And in the other corner, we have the zombie APIs that stand as forgotten relics of code, the remnants of a digital past that refuse to fade into oblivion.

Much like Neo’s epic journey to decipher the complexities of the Matrix, we’re about to embark on our own mission to uncover and understand these hidden threats. This quest will take us through the networks of APIs and into the core of your digital infrastructure, where the lines between security and vulnerability often blur. 

So, grab your trench coat and sunglasses. It’s time to get a move on!

What is a shadow API?

Shadow APIs are third-party application programming interfaces your organization hasn’t managed or secured, functioning outside your IT’s oversight. Much like digital stowaways in your digital infrastructure, these often go unnoticed and can be potentially harmful.

Shadow APIs typically emerge when developers, pushing for innovation and speed, integrate external services or create APIs beyond official protocols. They’re often a byproduct of the need for rapid development and the utilization of multiple tools and services, leading to a bypass of the standard review process. Despite their innocuous creation, the lack of oversight means they can become significant security liabilities.

Risks and realities

One primary concern with shadow APIs is data exposure which can potentially lead to breaches. Moreover, they may harbor unpatched vulnerabilities, outdated code, or security flaws unnoticed without regular reviews and updates. These vulnerabilities offer cyber attackers a gateway to infiltrate systems and access confidential data.

In numbers and narratives

A recent report indicates that cyberattacks targeting APIs have surged by 137% in 2023 compared to the year before. Industries such as healthcare and manufacturing are particularly vulnerable, with attackers drawn to the proliferation of devices under the Internet of Medical Things and the expanding API ecosystems in these sectors. 

Furthermore, the risks and repercussions of shadow APIs are not merely theoretical; they have tangible impacts. Organizations frequently uncover these hidden APIs only after experiencing a security incident, such as an unexpected data breach or unauthorized access, highlighting the need for proactive detection and management.

What is a zombie API?

Zombie APIs, often forgotten but far from gone, are APIs that have been deprecated or abandoned but remain accessible within your digital ecosystem. Unlike their shadow counterparts, zombie APIs were once approved and used but have since fallen out of regular use and maintenance. Unnoticed and often unmaintained, they linger in the system, posing unique challenges and security risks.

Lingering threats

The primary risk associated with zombie APIs is outdated security. Being out of sight, these APIs often miss critical security updates and patches, making them easy targets for attackers. They can become unintentional backdoors, offering access to systems with possibly outdated security protocols. This issue underscores the importance of secure onboarding and offboarding of IT resources, ensuring that access rights and API functionalities are updated as systems and personnel change to prevent unauthorized access. 

Moreover, because they were once legitimate parts of the system, they might still have access to sensitive data, increasing the risk of data breaches if exploited.

Concerns in numbers

According to the State of API Security Q1 2023 report from Salt Labs, API-related cyberattacks, including those targeting zombie APIs, have surged by 400% compared to the previous six-month period. This significant increase highlights the expanding threat landscape and the pressing need for organizations to address these latent vulnerabilities.

Spotting the differences

Understanding the difference between Shadow API and Zombie API is key to effectively managing their risks. While both are problematic and hidden threats within your digital infrastructure, their origins, behaviors, and the risks they introduce vary considerably.

Shadow vs. Zombie

  • Origin: Shadow APIs often emerge from rapid development cycles, necessitating enhanced shadow API detection strategies to identify these unauthorized elements that bypass official IT governance. They’re like unauthorized constructions within your digital city. In contrast, zombie APIs are the remnants of your infrastructure’s past — once approved and used APIs that have since been abandoned or replaced yet still linger unnoticed.
  • Risk profile: The primary risk of shadow APIs lies in their unknown nature, making shadow API discovery and security measures crucial to prevent potential exposure of sensitive data and API keys. On the other hand, zombie APIs represent a different kind of risk. They’re often outdated and unpatched, making them susceptible to known vulnerabilities attackers can exploit.

Unique impacts

  • Impact on security posture: Shadow APIs can introduce immediate and unpredictable risks, as they often go undetected until an incident occurs. Zombie APIs, while also a hidden threat, are typically more predictable because their vulnerabilities are often understood but ignored. The risk they pose increases over time as they become more outdated and further removed from current security practices.
  • Strategic approach: To effectively remediate shadow APIs, you need a strategy focused on rigorous scanning, discovery, and continuous monitoring to safeguard against risks. For zombie APIs, the focus should be on inventory management and regular updates or decommissioning of outdated systems.

Detecting the undetectable

Spotting shadow and zombie APIs can feel like a hide-and-seek game. Continuous monitoring keeps a constant watch on your system, flagging anything that doesn’t quite fit. Static code analysis is another essential tool, diving into your code to pinpoint vulnerabilities before they cause trouble.

Yet, it’s not all smooth sailing. To stay ahead, you must have continuous real-time monitoring in your arsenal and pair it with the thorough scrutiny of static code analysis.

But here’s a pro tip: keep your team and tools sharp with the latest know-how, and don’t forget to set the ‘normal’ scene for your APIs. Knowing what’s typically up can help you quickly spot when something’s amiss.

Remediation tactics

Here’s how you can effectively tackle the remediation of shadow and zombie APIs:

Immediate action plan:

  • Isolate and assess: Quickly contain the API, cutting off unauthorized access and assessing the extent of exposure.
  • Investigate: Determine how the API was introduced or why it was abandoned and identify any data or systems compromised.

Long-term strategies:

  • Regular audits: Conduct thorough audits to ensure ongoing shadow API detection and security, identifying any new or previously unnoticed APIs.
  • Employing secrets management tools: In the long-term strategy for securing APIs, organizations should mandate that API access and authentication are exclusively managed through secrets or JSON Web Tokens (JWTs). Following this, the features of secrets management tools will come in handy as these tools automate and fortify the handling of the authentication mechanisms. Additionally, implementing a monitoring solution is crucial, ensuring that all API interactions are continuously observed for anomalies, thus comprehensively reducing the risk profile.
  • Policy enforcement: Develop and enforce security policies that include regular reviews and updates, ensuring a proactive stance on shadow API security.

Proactive measures to minimize risks

Minimizing risks involves a proactive approach to API management and security:

Asset inventory

  • Comprehensive scanning: Regularly scan your digital environment to ensure complete shadow API discovery and inventory.
  • Documentation: Maintain detailed records of all APIs, including their purpose, data access levels, and security measures.

Reducing privileges

Implementing the least privilege principle for all APIs is crucial, ensuring they have only the necessary access and reducing the potential impact of a compromised API key. Complementing this, practicing secrets management in a zero-trust architecture is pivotal. This approach upholds the ‘never trust, always verify’ principle, significantly bolstering overall system security by verifying access and managing sensitive data securely. 

Continuous improvement

  • Stay updated: Keep abreast of the latest threats and trends in API security to adapt your strategies accordingly.
  • Educate and train: Regularly educate your team about the importance of API key security and best practices for shadow API detection and remediation.
  • Feedback loop: Create a system where lessons from security incidents are used to improve future security measures, reducing similar risks.

Entro: Enhancing API Security with Anomaly Detection

As we wind up, the key takeaway is clear: vigilance and proactive management are key to navigating the waters of shadow and zombie APIs. The risks they pose to your digital infrastructure are significant, but they can be effectively managed and mitigated with the right strategies and tools.

Enter Entro, a tool designed to navigate the complexities of API security. Entro excels in the detection, monitoring, and protection of secrets essential for API authentication. Its specialization in managing and safeguarding authentication secrets creates a secure barrier, preventing unauthorized access and enhancing the overall security of your API ecosystem.

Moreover, Entro’s anomaly detection feature leverages advanced machine learning algorithms to monitor secrets usage continuously, alerting you to abnormal behaviors that could signify a breach. Plus, when it comes to remediating issues, Entro’s insights and recommendations are invaluable, helping you reduce excessive privileges based on actual usage and ensuring your APIs operate securely and efficiently.


By integrating Entro into your security strategy, you gain a powerful ally in the fight against hidden threats. 

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