Modern applications rely on APIs but this make companies exposed to fresh security threats. The OWASP API Security Top 10 (2025) offers complete guidelines to detect API vulnerabilities while providing ways to fix them. This article examines each risk category alongside real-world attack scenarios and best practices to improve API security in micro services and distributed architectures (P. J. K et al., 2023).

Why API Security Matters More Than Ever, let’s dig in to it?

In my opinion, APIs power the backbone of modern digital innovation — enabling everything from cloud computing and mobile apps to IoT and AI-driven services. But as organizations scale their API ecosystems to meet user demands, these endpoints have become prime targets for cyberattacks. Without proper security measures, attackers exploit common API flaws such as:

· Broken authorization controls: Exposes sensitive data.

· Insecure authentication mechanisms: Allows unauthorized access

· Business logic flaws: Enables financial fraud or privilege escalation.

· Lack of rate limiting: Leads to denial-of-service (DoS) attacks.

Gartner predicts API-related breaches will cause 60% of web application attacks by 2025 thus making API security a top concern for security teams.

Are we ready for this? Let’s start this with our well known OWSAP top 10 2025 list.

API1: Broken Object Level Authorization (BOLA)

• Attackers are able to manipulate API endpoints in order to gain access to data they should not have.
• Example: A malicious user changes an API request from /user/123 to /user/124 and steals information belonging to another user.

Solution: Strict access controls and object level authorization checks should be put in place.

API2: Broken Authentication

• APIs in question have poorly configured authentication protocols.
• Example: API keys are directly placed in mobile applications and thus can be easily obtained.

Solution: Require OAuth 2.0, OpenID Connect (OIDC), and MFA for authenticating APIs.

API3: Broken Object Property Level Authorization (BOPLA)

• Attackers gain access to modify restricted fields because access controls are not properly enforced.
• Example: In an API request, a user attempts to change their role from “user” to “admin” through editing an API request.

Solution: Restrict editable properties and enforce granular access control checks.

API4: Unrestricted Resource Consumption

• Failure to incorporate rate limiting in APIs results in systems being overloaded by attackers.
• Example: Through application programming interfaces, bots conduct million-dollar API requests which create DoS attacks.

Solution: A rate limiting scheme together with request throttling and quota enforcement needs to be put in place.

API5: Broken Function Level Authorization (BFLA)

• Attackers make unauthorized API function calls because of poorly configured permissions.
• Example: Low privileged user gain access to admin only API endpoints.

Solution: Enforce role-based access control (RBAC) and implement least privilege policies.

API6: Unrestricted Access to Sensitive Business Flows

• Business logic vulnerabilities in APIs are manipulated by attackers.
• Example: Hackers take advantage of an API bug to change transactions or refund requests.

Solution: Perform business logic abuse testing and apply behavioural analysis.

API7: Server-Side Request Forgery (SSRF)

• Through APIs, attackers gain access to internal resources and cloud metadata endpoints.
• Example: Through malicious API requests AWS IAM credentials are accessed via cloud instance metadata.

Solution: Enforce restrictions on API outbound requests; use firewall rules to block unauthorized connections.

API8: Security Misconfiguration

• APIs that use default credentials coupled with verbose error messages and poor CORS security are potentially data breaches.
• Example: Public APIs return detailed stack traces and internal server information.

Solution: Enforce safe default configurations and enforce least privilege permissions.

API9: Improper Inventory Management

• Organizations are vulnerable to increased attack surfaces due to failure in documenting, monitoring and deprecating old APIs.
• Example: A legacy API uses insecure authentication during production.

Solution: Create an API inventory, retire inactive APIs and implement version management.

API10: Unsafe Consumption of Third-Party APIs

• Applications are prone to supply chain attacks as a result of trusting third party APIs blindly.
• Example: A third-party payment API that has been compromised steals users’ financial information.

Solution: Validate API inputs, sanitize response data from APIs and track third party dependencies.

Best Practices for Securing APIs in 2025.

1. Enforce Zero Trust API Security

• Every request must be authenticated (OAuth 2.0, JWT, and mTLS).
• Implement continuous API risk detection and response via least privilege access controls to minimize API exposure.
• Perform continuous API risk assessment through the utilization of security automation tools.

2. Secure API Gateways & Reverse Proxies

• Deploy centralized security controls through API gateways such as Kong, Apigee, and AWS API Gateway.
• Enforce strict schema validation to prevent malformed API payloads.
• Geo-fencing rules need to be strictly implemented to locate and restrict API access.

3. Implement API Security Testing in CI/CD Pipelines

• Run API security scans automatically with DAST tools along with Manual pen testing.
• Use SAST (Static Application Security Testing) for API code reviews.
• Red team exercises need to be conducted to simulate API abuse scenarios.

Let’s analyse a case study for our learning to prevent an API Breach in a Healthcare Platform.

Scenario: There is an API data breach at a healthcare provider exposed patient records because of broken object-level authorization (BOLA).

Why Is this critical in Healthcare?

We all know Patient Identifiable (PII) and health records (PHI) data should be protected under laws like HIPAA. Exposing them due to BOLA could lead to:

· Identity theft

· Loss of patient trust

· Legal penalties

· Reputational damage

Lessons learnt and remediation steps:

• Enabled role-based access control (RBAC) and fine-grained access controls.
• Implemented rate limiting and API monitoring to detect unusual access patterns.
• Continuous threat detection came from API security posture management systems like Salt Security and Traceable AI.
• New vulnerabilities in APIs should be regularly monitored and tested.
• Authentication and authorization should be enforced with strong authentication and authorization based on Zero Trust principles.
• AI-driven API security solutions should be adopted for real time threat detection.

Outcome: The organization saw an 85% decrease in API security incidents and fulfilled all HIPAA requirements by having the above security controls.
Reference:
P. J. K, C. C. A, E. R., and S. S., “Guarding Against Data Breach,” 2023 Intelligent Computing and Control for Engineering and Business Systems (ICCEBS), Chennai, India, 2023, pp. 1–5, Doi: 10.1109/ICCEBS58601.2023.10449222.