Strengthening the Backbone of Modern Applications
APIs have become the backbone of modern digital ecosystems and development practices, connecting everything from customer portals and mobile apps to payment systems and healthcare platforms. But as organizations continue to build and innovate, APIs have become one of the most frequently targeted points of attack, with nearly every organization suffering from API-related breaches.
A single insecure API can expose sensitive data, disrupt operations, or create cascading risks across interconnected systems, amplifying both technical and business impact. Protecting them requires more than a single control; it demands continuous visibility, rigorous validation, and close collaboration between development and security teams throughout the lifecycle.
Table of Contents
Understanding APIs and the Risks They Introduce
Application Programming Interfaces, or APIs, are the invisible framework that connects modern digital ecosystems.
They enable software systems to communicate, allowing mobile apps to access data from servers, enabling payment gateways to verify transactions, and letting businesses integrate third-party tools and services.
They power innovation and efficiency, but their openness also makes them prime targets for attackers.
Research by Akamai found that 84% of surveyed security professionals have experienced an API security incident over the past 12 months.
- Akamai's 2024 API Security Impact Study
In recent years, threat actors have increasingly exploited insecure APIs to steal data, hijack user sessions, or disrupt business operations. Common risks include misconfigured authentication, excessive data exposure, and lack of rate limiting, issues that can expose entire databases or systems through a single vulnerable endpoint. Further, the rise of “shadow APIs,” which are undocumented or forgotten by development teams, has expanded the attack surface, leaving organizations blind to potential entry points.
Types of APIs and Their Use Cases
APIs come in several forms, each serving a distinct purpose in how systems communicate and exchange data.
- Open APIs (Public) are made available to external developers or third parties, often to encourage innovation or integration with external platforms. Because they are publicly accessible, they require strict authentication, throttling, and monitoring to prevent misuse or data leaks.
- Internal APIs (Private) operate within an organization’s network and are used to connect internal systems and services. Although not externally exposed, they can still be exploited if improperly configured or if access controls are too permissive.
- Partner APIs enable communication between trusted business partners, such as payment processors or logistics providers. They typically use authentication mechanisms like OAuth 2.0 or mutual TLS to ensure that only verified entities can interact with the data.
- Composite APIs combine multiple endpoints into a single call, allowing developers to retrieve data from different services simultaneously. While they improve efficiency, they can also expand the potential attack surface if one component lacks proper validation or authorization controls.
No matter the type, each one must be designed and maintained with the same level of scrutiny. When every API is treated as a high-value asset, security becomes a matter of consistent process, not an exception.
Five Best Practices to Strengthen API Security
To truly protect your environment, you must adopt a continuous, lifecycle-based strategy to API security. Below are five best practices that form the foundation of a strong security posture, balancing developer speed with security rigor.
#1- Implement Strong Authentication and Authorization
Authentication and authorization form the first line of defense for any API. Yet, many breaches occur because APIs rely on weak or inconsistent credential management. Every API call should require authentication, ideally through modern standards like OAuth 2.0 or OpenID Connect. Avoid using static keys or embedding credentials directly in code repositories.
Authorization should be enforced on every endpoint and resource. Role-Based Access Control (RBAC) or Attribute-Based Access Control (ABAC) ensures users can only perform actions and access data aligned with their permissions. Never assume trust between internal services; enforce least privilege even within private APIs.
#2 - Enforce Input Validation and Data Sanitization
Unvalidated inputs are a common path for injection attacks, data corruption, and system compromise. Every API should validate input against expected formats, lengths, and data types before processing. Using schema validation frameworks like OpenAPI or JSON Schema helps automate these checks and prevent malformed or malicious payloads from reaching backend systems.
Beyond validation, ensure output encoding and sanitization to prevent cross-site scripting (XSS) and data leakage. Remember, attackers don’t always target the obvious inputs; they look for inconsistencies in nested objects, parameters, or headers.
#3 - Limit Data Exposure and Use the Principle of Least Privilege
APIs often overexpose data by returning unnecessary fields, verbose error messages, or complete object structures. This excessive exposure not only increases the risk of data leaks but also gives attackers valuable insights into backend logic.
Always design responses to return only what’s necessary for a given function. Implement field filtering, object-level access controls, and response masking to protect sensitive information. Additionally, avoid exposing internal identifiers or stack traces in error responses; these should be logged internally, not shared externally.
#4 - Secure and Monitor the API Gateway
The API gateway acts as the control point for all API traffic and is crucial for enforcing security policies. Use it to implement centralized authentication, rate limiting, IP filtering, and threat detection. A well-configured gateway prevents common issues like denial-of-service (DoS) or brute-force attempts from overwhelming backend services.
Equally important is continuous monitoring. Log every API transaction and integrate logs with your SIEM to identify anomalies such as unusual access patterns or data exfiltration attempts. Pairing this with behavioral analytics allows faster detection of credential abuse or compromised tokens.
#5 - Maintain Continuous Testing and Version Control
APIs are dynamic, new endpoints are added, deprecated ones linger, and dependencies evolve. Continuous testing ensures that security doesn’t fall behind development. Incorporate API-specific scans and fuzzing into CI/CD pipelines, and use penetration testing to uncover hidden weaknesses.
Version control also plays a key role. Deprecated or outdated API versions should be retired promptly to prevent attackers from targeting legacy vulnerabilities. Always document changes thoroughly and communicate version updates to both internal and external consumers.
APIs will always be a target, but with continuous validation, intelligent monitoring, and disciplined governance, they can also become one of the strongest links in your cybersecurity strategy.
Establishing API Governance and Ownership
Technical controls alone aren’t enough to secure APIs; governance ensures those controls are applied consistently and effectively. Many organizations struggle not because they lack tools, but because ownership is unclear.
In fact, only one-third of APIs are being managed by a centralized operations team. When they’re deployed without centralized oversight, shadow endpoints emerge, standards diverge, and risk multiplies.
Organizations face significant API governance gaps, with 78% saying that they don't know how many APIs they have in their IT ecosystem.
- Axway's The State of Enterprise API Maturity in 2024 Report
Effective governance begins with visibility and accountability. Every organization should maintain a living API inventory that maps ownership, classification, authentication method, and data sensitivity for each interface. This inventory should integrate directly with vulnerability management and exposure tracking workflows, allowing security teams to continuously validate API posture and remediation status alongside other assets.
Ownership must be clearly assigned. Product teams should own the security and lifecycle of APIs they deploy, while security leadership defines and enforces global policy. This includes:
- Defining authentication, authorization, and encryption standards based on sensitivity and exposure.
- Ensuring APIs undergo security testing during every release through CI/CD integration.
- Establishing deprecation policies to retire outdated versions before they become unmonitored entry points.
Governance should not slow innovation; it should enable it by standardizing and automating security. By embedding policies into CI/CD pipelines and aligning with frameworks like OWASP API Security Top 10 and NIST SP 800-204, organizations can ensure every API follows the same validation, monitoring, and logging requirements by default.
Securing APIs Through The DevSecOps Framework
Every API endpoint represents both an opportunity and a potential vulnerability. As organizations expand their digital ecosystems, unmanaged APIs can quickly become one of the largest sources of cyber risk. Addressing that risk requires a framework that unites development speed with continuous security discipline.
This is exactly what the DevSecOps framework was built to accomplish. DevSecOps brings development, security, and operations together under a single goal: delivering secure, high-performing applications at the speed of business.
By aligning API security with these principles and adopting DevSecOps, organizations ensure that security and innovation move forward in lockstep. When security becomes part of every build, every release, and every test, organizations gain the visibility and confidence to innovate without compromise.
Adopt DevSecOps to make security a constant, not a checkpoint.
FAQs About API Security
Why has API security become such a major concern for organizations?
APIs now power the majority of digital interactions, connecting cloud applications, mobile platforms, and third-party integrations. As more data and functionality are exposed through these interfaces, attackers increasingly target them to steal credentials, exfiltrate data, or disrupt services. Without continuous testing and proper governance, APIs can unintentionally create open doors into critical systems.
What are the most common causes of API-related breaches?
Most API breaches stem from misconfigurations, weak authentication, excessive data exposure, and a lack of input validation. Inconsistent development practices, shadow APIs, and unmonitored endpoints also contribute heavily to risk. Because APIs evolve rapidly, security controls must evolve in parallel through automation and lifecycle-based monitoring.
How does API governance reduce risk?
Governance ensures visibility and accountability. By maintaining an accurate inventory of all APIs, assigning clear ownership, and enforcing consistent policies, organizations can close blind spots that attackers exploit. Integrating governance into DevSecOps workflows ensures every new or updated API undergoes validation, testing, and version control before production deployment.
What role does DevSecOps play in API security?
DevSecOps integrates security directly into the development lifecycle, embedding automated testing, secure coding standards, and validation checks into every release. This approach eliminates the delays of traditional post-deployment testing and ensures vulnerabilities are caught early, without slowing developer velocity. API security, in this model, becomes a shared responsibility across engineering and security teams.
How can organizations continuously test and monitor APIs?
Continuous validation can be achieved by integrating API security scans, fuzzing, and penetration testing into CI/CD pipelines. Monitoring should be centralized through an API gateway and SIEM to track anomalies such as unauthorized access, token misuse, or data exfiltration. Regular reviews of logs, performance metrics, and version control repositories help maintain visibility into new or deprecated endpoints.
What’s the difference between API security and traditional application security?
Traditional application security focuses on protecting the application as a whole, while API security targets the interfaces that connect those applications. APIs expand the attack surface beyond the app itself, often bridging multiple systems and vendors. This makes continuous validation, strict authentication, and least-privilege design essential to securing interconnected environments.
