Shadow APIs and Zombie APIs are Common in Every Organizations’ Growing API Attack Surface

By Doug Dooley, COO, Data Theorem

The rise of cloud-native applications has revolutionized the way businesses operate, enabling them to scale rapidly and stay agile in a fast-paced digital environment. However, the increasing reliance on Application Programming Interfaces (APIs) to connect and share data between disparate systems has also brought new risks and vulnerabilities to the forefront. With every new API integration, the attack surface of an organization grows, creating new opportunities for attackers to exploit vulnerabilities and gain access to sensitive data.

This article will attempt to shed some more light on:

  • API Attack Surfaces
  • Shadow APIs
  • Zombie APIs
  • API Protection

APIs have become the backbone of modern digital ecosystems, allowing organizations to streamline operations, automate processes, and provide seamless user experiences. They are the data transporters for all cloud-based applications and services. APIs act as intermediaries between applications, enabling them to communicate with each other and exchange data. They also provide access to critical services and functionality in your cloud-based applications. If an attacker gains access to your APIs, they can easily bypass security measures and gain access to your cloud-based applications, which can result in data breaches, financial losses, and reputational damage. For hackers looking to have the best return on investment (ROI) of their time and energy for exploiting and exfiltrating data, APIs are one of the best targets available today.

It’s clear these same APIs that enable innovation, revenue, and profits also create new avenues for attackers to achieve successful data breaches for their own financial gains. As the number of APIs in use grows, so does the attack surface of an organization. According to a recent industry study by Enterprise Strategy Group (ESG) titled “Securing the API Attack Surface”, the majority (75%) of organizations typically change or update their APIs on a daily or weekly basis, creating a significant challenge for protecting the dynamic nature of API attack surfaces.

API security is critical because APIs are often the important link in the security chain of modern applications. Developers often prioritize speed, features, functionality, and ease of use over security, which can leave APIs vulnerable to attacks. Additionally, cloud-native APIs are often exposed directly to the internet, making them accessible to anyone. This can make it easier for hackers to exploit vulnerabilities in your APIs and gain access to your cloud-based applications. As evidence, the same ESG study also revealed most all (92%) organizations have experienced at least one security incident related to insecure APIs in the past 12 months, while the majority of organizations (57%) have experienced multiple security incidents related to insecure APIs during the past year.

One of the biggest challenges in protecting an API environment is the proliferation of Shadow APIs. Shadow APIs are APIs that are used by developers or business units without the knowledge or approval of IT security teams. These APIs can be created by anyone with the technical knowledge to build them, and because they are not managed by the IT department they are often not subject to the same security controls and governance policies as officially sanctioned APIs.

Shadow APIs lack clarity of priority, ownership, and security policy controls. They often have a business purpose such as supporting features in a mobile and web applications, but no one is sure whether these APIs are running in production or non-production, who the clear owners are, and which security policy controls should be applied to protect them from attack. For example, a developer may create an API to streamline a workflow, or a business unit may create an API to integrate a third-party application. However, when these APIs are not properly vetted, tested, and secured, they can pose a significant risk to the organization. Shadow APIs can introduce vulnerabilities, such as unsecured endpoints, weak authentication mechanisms, and insufficient access controls, which can be exploited by attackers to gain unauthorized access to sensitive data.

Another challenge facing organizations is the emergence of Zombie APIs. Zombie APIs are APIs that are no longer in use but are still active on the network and running in the cloud. These APIs can be left over from legacy systems, previous versions of the API, or retired applications; or they may have been created by developers who have since left the organization. Zombie APIs can be particularly dangerous because they may not be monitored or secured, making them vulnerable to exploitation.

While Zombie APIs do not have a clear business purpose, they consume resources, can add an expense for organizations, and create additional attack surface. For example, a Zombie API can be an older version of an API that is no longer connected to its original application but left in place for potential backward compatibility reasons. However, over time that legacy API is forgotten, yet its underlying resources (compute, storage, databases) that fuel the API’s operations are left running without proper oversight, maintenance, and security hardening. Attackers can use these APIs to gain unauthorized access to sensitive data, bypass security controls, and launch lateral movement attacks against other systems on the network. Zombie APIs can also be used to launch Server-Side Request Forgery (SSRF) or remote code execution (RCE) attacks, which can bring down entire systems and cause significant damage to an organization’s reputation as seen with the Capital One Breach and Log4shell global exploits, respectively.

To mitigate the risks posed by Shadow and Zombie APIs, organizations must take a proactive approach to API management and security. This includes developing a comprehensive API management strategy that includes security controls, active monitoring, and reporting capabilities.

One key aspect of API management is the establishment of a centralized API inventory catalog. This catalog should include all approved APIs, along with information about their functionality, usage, and security controls. This can help IT and security teams identify Shadow APIs and Zombie APIs, as well as track and monitor API usage to ensure compliance with governance policies.

Another important aspect of API management is the implementation of security controls. These may include encryption, access controls, authentication mechanisms, and threat detection and response capabilities. Security controls should be implemented at all layers of the API stack, from the application layer to the transport and infrastructure service layers, to ensure that APIs are protected against a wide range of attacks.

In addition, organizations should also implement scanning, observability, dynamic analysis and reporting capabilities to detect and respond to API-related threats. This may include real-time scanning of API usage, logging and run-time analysis of API activity, and alerting and reporting capabilities to notify IT and security teams of potential threats.

When it comes to securing APIs and reducing attack surfaces, Cloud Native Application Protection Platform (CNAPP) is a newer security framework that provides security specifically for cloud-native applications by protecting them against various API attacks threats. CNAPPs do three primary jobs: (1) artifact scanning in pre-production; (2) cloud configuration and posture management scanning; (3) run-time observability and dynamic analysis of applications and APIs, especially in production environments. With CNAPP scanning pre-production and production environments, an inventory list of all APIs and software assets is generated. If the dynamically generated inventory of cloud assets has APIs connected to them, Shadow or Zombie APIs can be discovered. As a result, CNAPPs help to identify these dangerous classes of APIs and help to add layers of protection to prevent them from causing harm and exposure from vulnerable API attack surfaces.

Ultimately, the key to managing the risks posed by expanding API attack surfaces with Shadow and Zombie APIs is to take a proactive approach to API management and security. When it comes to cloud security, CNAPP is well suited for organizations with cloud-native applications, microservices, and APIs that require application-level security. API security is a must-have when building out cloud-native applications, and CNAPP offers an effective approach for protecting expanding API attack surfaces, including those caused by Shadow and Zombie APIs.

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