What are shadow APIs?
Shadow APIs are undocumented, unmanaged, or unknown API endpoints that operate outside official IT oversight and security controls. More often than not, shadow APIs emerge from rapid development; inconsistent, nonexistent, or unnecessarily cumbersome API documentation processes; and unmonitored third-party integrations.
While not inherently malicious, shadow APIs exist without enterprise-level approval. As a result, they lack visibility and governance, making them invisible to security controls that are typically applied to their documented counterparts, like authentication, input and schema validation, rate limiting, encryption in transit, and regular updates.
Quick note: Shadow APIs are entirely different from ShadowRealm APIs (or Realms API), a JavaScript proposal aimed at improving isolation for JavaScript-based environments.
Advanced API Security Best Practices [Cheat Sheet]
Download the Wiz API Security Best Practices Cheat Sheet and fortify your API infrastructure with proven, advanced techniques tailored for secure, high-performance API management.
Why and how do shadow APIs emerge in modern software development environments?
Rapid release cycles
The need to stay competitive and deliver new software or updates quickly can tempt well-meaning developers to ignore long-term API security risks for immediate results. For example, when a developer needs to fetch data from a third-party integration, test a new product, or debug software at breakneck speed? Shadow APIs become the ready alternative.
Decentralized teams
Disjointed teams duplicate APIs due to lack of communication. For instance, developers create and document an API for extracting data from a third-party integration. Ops or security teams need the same data and go ahead and replicate APIs, leaving the newest additions ungoverned.
Cloud-native autoscaling / ephemeral resources
Securing the cloud’s ephemeral resources is challenging for most organizations. And infrastructure-as-code (IaC) scripts, CI/CD pipelines, and container autoscaling make workloads ephemeral, which can lead to new or modified API routes being deployed without timely updates to the central API inventory.
Pro-tip: The Wiz Container Security Guide offers hands-on solutions for protecting ephemeral resources.
Microservices and API sprawl
Microservices architectures expose hundreds or thousands of API endpoints across distributed systems. As services scale horizontally, traditional API management tools fail to keep up, leaving some APIs undocumented and expanding the attack surface.
Abandoned and zombie APIs
Deprecated APIs and zombie APIs (APIs that are known but unmaintained) are sometimes left running for phased rollouts, for test scenarios, or “just in case.” A lot of times, these APIs are forgotten and left untracked, introducing unmanaged risks.
Shadow API security risks and challenges
Shadow APIs pose significant threats to application and data security, regulatory compliance, and business continuity. Here’s how:
Attack vectors and data exposure
Shadow APIs either completely bypass API gateways or exist behind gateways but miss proper security controls like authentication, input/output validation, and rate limiting, providing a perfect breeding ground for attack vectors like the OWASP API Security Top 10 risks.
How do shadow APIs contribute to these API security risks?:
Consider broken-object level authorization (BOLA — API1:2023), where APIs don’t properly verify user permissions before granting access to sensitive objects, and
Broken object property-level authorization (BOPLA — API3:2023), which occurs when APIs return more data than required.
Because shadow APIs often have poor access controls and are deployed without being subjected to secure design reviews (which would have uncovered the risks beforehand), both BOLA and BOPLA are common.
Real-world shadow API breach examples abound, demonstrating how API governance gaps allow data exfiltration, privilege escalation, and lateral movement. A clear example is the T-Mobile breach, where a single API lacking proper access control exposed 37 million customer records for more than 40 days, resulting in significant reputational and compliance impacts that caused severe damage to a company that was still recovering from compliance fines related to a previous breach.
What Is Shadow IT? Causes, Risks, and Examples
Shadow IT is an employee’s unauthorized use of IT services, applications, and resources that aren’t controlled by—or visible to—an organization’s IT department.
Read more
Compliance and regulatory risks
Security frameworks like NIST (e.g., SP 800-53), ISO/IEC 27001, SOC 2, HIPAA, PCI DSS, and GDPR require organizations to enforce data privacy and maintain accurate inventories of assets and data flows—including APIs—while documenting security controls and performing regular audits.
Shadow APIs’ lack of security oversight creates compliance blind spots that make it impossible to fulfill these regulatory requirements.
Business impact and financial consequences
In 2025, the average cost of a breach dropped to approximately $4.44 million from $4.48 million, excluding lawsuit costs and long-term reputational damage. Early detection and containment are largely responsible for this drop, but those factors aren’t part of the equation when it comes to shadow APIs.
Because shadow APIs are unknown and unmonitored, quickly finding the source of a shadow API breach and mitigating it just isn’t feasible. Remember: The T-Mobile breach was discovered after 40 days!
Shadow API detection, prevention, and mitigation strategies
The only path forward? Addressing shadow APIs at the source. That’s why you need to implement policies that prevent their creation and enforce these policies autonomously.
Follow the strategies highlighted below for effective shadow API prevention:
Implement comprehensive API governance
API governance brings all APIs under centralized management. To establish complete API governance:
Use policy as code (PaC) to enforce standardized policies and processes, detailing who creates APIs and how, API approval processes, compulsory API security controls, and API lifecycle management.
Institute API-first development practices that require endpoint registration before deployment. These include mandating API documentation via OpenAPI spec and enforcing version management processes to abstract zombie APIs.
Employ shift-left security by integrating OpenAPI contracts and policy enforcement into CI/CD pipelines to prevent undocumented or insecure APIs from reaching production.
Enforce contract testing (e.g., schema diff / block on drift) in CI pipelines to ensure consistency and prevent undocumented API changes from reaching production.
Graph context for prioritization: Use graph-based correlation to highlight shadow endpoints that are externally reachable, touch sensitive data, or sit on critical paths.
Adopt zero-trust principles (e.g., aligned to NIST SP 800-207) through measures like:
Service mesh with mTLS, which encrypts all service calls
JWT validation with request authentication for secure user-to-API requests
API key/token rotation and permission scoping to contain the blast radius of API compromise
Least privilege for service accounts to deny unauthorized services and namespaces by default
Enforce continuous inventory and automated discovery
To eliminate the visibility gaps that come with point-in-time monitoring, implement continuous rather than scheduled API discovery. Next, add ownership attribution to your real-time API inventories to facilitate accountability.
Automated discovery tools are your best bet here because they continuously uncover, tag (for ownership, SLAs, domain), and catalog APIs at every phase of the SDLC. Pick a tool that employs multiple API discovery mechanisms like runtime telemetry (e.g., eBPF), gateway/WAF logs, cloud audit and access logs, attack surface scanning, and code-centric approaches (e.g., SAST, IAST, and route extraction).
Deploy API gateways
Applying API runtime security controls individually creates inconsistencies. Instead, make API gateways truly act as the single point of entry for all API calls. This involves:
Anchoring API monitoring, logging, and analytics at the gateway to seamlessly track APIs lacking security controls and compliance
Implementing gateway schema validation and centralized authentication/authorization (e.g., OIDC/OAuth scopes) to ensure requests conform to contracts, enforce least privilege, and block non-conforming traffic by default
(Keep in mind that not all shadow APIs “bypass” gateways; many exist behind gateways but miss proper policies, so it’s best practice to implement gateways alongside other security controls.)
Watch 5-minute demo
Watch the demo to learn how Wiz Code scans infrastructure as code, container images, and CI/CD pipelines to catch risks early—before they reach the cloud.
Watch now
Establish developer education and secure coding practices
Regularly educate development teams on the risks of shadow APIs and the need for secure coding practices.
Empower developers to take responsibility for securing their own code/deployments by providing actionable security feedback in their preferred channels (especially in their IDE) and self-service remediation (e.g., one-click or guided fixes).
Embed API security into DevSecOps workflows
Don’t slow down development velocity to ensure API security. Take the DevSecOps route instead:
Integrate API security tools into precommit hooks for pre-deployment code scans.
Automate API documentation, tagging, and encryption.
Automate security testing in CI pipelines.
Review pull requests for undocumented or vulnerable APIs and automatically block/fix them.
The Wiz API Cheat Sheet offers a clear roadmap towards tackling shadow APIs and all other API risks.
The Wiz approach to shadow API security
Getting comprehensive visibility into all API endpoints across multi-cloud environments doesn’t have to be hard—particularly when you have the right tool. Wiz offers:
Always-on API discovery
Unified governance
Validation of real exposure: Wiz pairs discovery with dynamic validation to confirm whether undocumented endpoints are externally reachable and exploitable before escalating.
Wiz Code also integrates IaC scanning, secrets detection, and CI/CD security controls with development workflows to stop shadow APIs from reaching production. Taking API security a step further, the Wiz Security Graph connects cloud resources to their source code, enabling teams to trace shadow APIs back to their origin and implement fixes at the source.
Additionally, Wiz's attack path analysis helps prioritize shadow API risks by showing how undocumented endpoints could be exploited in real attack scenarios.
Ready to uncover and control shadow APIs across code, cloud, and runtime? See how Wiz discovers APIs continuously, validates real exposure, and prioritizes what to fix first—book a demo.
Catch code risks before you deploy
Learn how Wiz Code scans IaC, containers, and pipelines to stop misconfigurations and vulnerabilities before they hit your cloud.
