Shadow APIs: Understanding the Risk and 6 Ways to Reduce It

What Is a Shadow API? 

A shadow API is an application programming interface that is created or used without explicit approval from the organization’s IT or security teams. Shadow APIs can emerge from various sources, including developers experimenting with new features, legacy systems that are no longer officially supported but still in use, or services integrated outside of formal IT channels. 

Unlike official APIs, shadow APIs lack oversight and governance, making them invisible to the security measures typically applied to known and documented APIs. They operate under the radar of standard security and monitoring practices. Because these APIs were not introduced through sanctioned processes, they are excluded from inventory or documentation efforts. 

As a result, shadow APIs present significant risks. They are not subjected to regular security assessments, patches, and compliance checks that would normally be part of an API’s lifecycle management in a secure software development environment.

This is part of a series of articles about API security

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Why Are Shadow APIs Dangerous?

Shadow APIs can result in the following issues:

• Data exposure: Unauthorized interfaces can inadvertently allow access to sensitive information. They are not monitored or managed by an organization’s IT security protocols, easily becoming gateways for data breaches. They also lack encryption, authentication mechanisms and access controls.
• Lateral movement: Shadow APIs can serve as entry points for attackers to navigate through a network. Once inside, attackers can exploit these APIs to move sideways within the network, accessing sensitive systems and far beyond their initial point of entry.
• Unpatched vulnerabilities: Outside of official oversight, these APIs may miss critical patches for newly discovered vulnerabilities, leaving them open to exploitation. Attackers can leverage these weaknesses to gain unauthorized access or perform malicious actions, exploiting the gap between vulnerability disclosure and patch application.
• Compliance and data privacy concerns: Organizations are obligated to adhere to various data protection regulations such as GDPR, CCPA, and HIPAA, which mandate strict controls over how personal data is collected, stored, and processed. Shadow APIs can inadvertently violate these regulations by failing to implement necessary security measures or by handling data in non-compliant ways. Such risk exposure of sensitive information and subject organizations to fines and legal penalties.

Related content: Read our guide to API attacks

Tzvika Shneider

CEO, Pynt

Tzvika Shneider is a 20-year software Security industry leader with a robust background in product and software management.

Tips from the expert

• Conduct regular network traffic analysis: Regularly analyze network traffic to identify anomalies and unexpected API endpoints that may signal the existence of shadow APIs.
• Engage in cross-team collaboration: Foster collaboration between development, security, and IT teams to ensure that all APIs are documented and managed appropriately, reducing the chance of shadow APIs emerging.
• Incorporate security training for developers: Provide ongoing security training for developers to raise awareness about the risks of shadow APIs and promote secure API development practices.
• Utilize API security posture management tools: Employ tools that continuously monitor and assess the security posture of your API environment, providing real-time alerts on unauthorized or risky APIs.
• Establish a shadow API response protocol: Create a clear response protocol for when shadow APIs are discovered, including steps for documenting, assessing, and securing these APIs promptly.

Shadow APIs vs. Zombie APIs

Shadow APIs and zombie APIs represent different challenges within an organization’s API ecosystem. While both pose security risks, their nature and the threats they introduce vary significantly. 

Shadow APIs are active but unmanaged and undocumented, created or used without the IT department’s knowledge. This lack of oversight means they can be exploited by attackers due to unknown vulnerabilities or inadequate security controls.

Zombie APIs refer to those that were once actively managed but have since been deprecated or abandoned; however, they remain accessible online. Despite being known to the organization at some point, these APIs are no longer updated or monitored, making them attractive targets for malicious actors seeking to exploit outdated security measures.

6 Ways to Avoid Shadow API Risks

Here are some of the measures that organizations can take to mitigate the risks of shadow APIs.

1. Perform Automated API Discovery and Testing

Automated API discovery tools scan an organization's network to identify all active APIs, including shadow APIs. These tools use techniques such as network traffic analysis, code scanning, and machine learning to detect APIs that may not be documented or known to the IT department. By continuously monitoring the network, these tools can uncover shadow APIs that have been introduced without proper authorization.

Once identified, automated testing tools can evaluate the security posture of these APIs. Automated testing involves running a suite of tests to check for common vulnerabilities, compliance with security policies, and proper implementation of authentication and encryption. This ensures that any discovered APIs are secure and adhere to organizational standards, reducing the risk of exploitation.

2. Enforce API Governance Policies 

Establish a framework that outlines how APIs should be created, managed, and retired within an organization. This process starts with defining clear standards for API development, including security protocols, data handling practices, and compliance requirements. 

By setting these standards, organizations ensure that all APIs, regardless of their origin or purpose, adhere to a uniform set of guidelines that mitigate risk and enhance security. Enforcement of these policies is also critical. Organizations must implement tools and audits to monitor compliance with governance standards across all API activities. 

3. Implement an API Gateway

An API gateway helps in managing and securing APIs, acting as a central point of entry for all API traffic. This enables greater control, monitoring, and security of APIs. By routing all requests through the gateway, organizations gain visibility into their API landscape, enabling them to identify unauthorized or rogue APIs quickly. 

The gateway also provides a layer of abstraction between clients and backend services, simplifying endpoint management and enhancing security protocols. Its security features, including authentication, authorization, rate limiting, and threat protection, help prevent unauthorized access and mitigate potential attacks on APIs. 

4. Consider Automation for API Documentation 

Automating API documentation helps in maintaining accurate and up-to-date information on all APIs within an organization, including shadow APIs. Automation tools can generate documentation directly from the source code and API definitions, ensuring that any changes in the API are immediately reflected in the documentation. 

Automated, real-time updates can eliminate discrepancies between the API’s current state and its documented capabilities, reducing the risk of security vulnerabilities caused by outdated or incomplete information. They also supports better collaboration among development, security, and operations teams by providing a single source of truth about API functionality and security. 

5. Regularly Audit and Update the API Inventory 

An API inventory acts as a central repository that lists all APIs within an organization, including their endpoints, functionalities, security measures, and dependencies. This enables organizations to maintain a holistic view of their API landscape, making it easier to identify shadow APIs that might otherwise go unnoticed. 

By conducting regular audits of this inventory, companies can assess the compliance of each API with established security policies and governance frameworks, quickly addressing any deviations. Auditing processes involve systematic examinations of how APIs are used, who accesses them, and whether any vulnerabilities have been introduced or exploited. 

6. Use Outbound API Proxies 

Outbound API proxies act as intermediaries for all outbound API traffic, offering a centralized point for monitoring and controlling external API calls. By intercepting these calls, they provide an opportunity to log each request and response, automatically documenting the interaction with external services. 

This mechanism helps identify shadow APIs by cataloging all outgoing communications, revealing which external APIs are being used and how they are being called. API proxies also introduce an additional layer of security by enabling thorough inspection of API traffic before it leaves the organization. However, they can potentially impact performance due to the additional processing required for each API call. 

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API Discovery and Security Testing with Pynt

Pynt's approach to API security emphasizes a 'shift-left' methodology, focusing on early discovery and resolution of vulnerabilities. This proactive stance in the software development life cycle allows for:

• Early Detection: Identifying API vulnerabilities early in the development process, reducing potential security risks.
• Comprehensive API Discovery: Automated discovery of APIs, ensuring complete visibility from development to production, crucial for identifying shadow APIs and other hidden risks.

• Leverages functional tests to detect complex business logic scenarios, providing targeted security insights.
• Seamless CI/CD Integration: Facilitating easy integration with existing development tools and pipelines, enhancing developer productivity without compromising security.

These aspects collectively enhance the overall security posture by addressing API vulnerabilities at their inception, rather than as an afterthought.

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