What is REST API security?
REST API security is the combination of technologies and practices used to safeguard RESTful endpoints from attacks, such as unauthorized access, exploitation, and abuse.
REST APIs are built on standardized and stateless principles, which is why they’re powerful and easy to develop. The downside? Those aspects leave API endpoints inherently exposed to misuse. In particular, REST APIs rely heavily on HTTP semantics—such as methods, headers, and response codes. That makes them straightforward to interact with but also brings risks like improper method handling and status code leakage.
Since APIs are the main interface for cloud-native apps, they have become a prime target for attacks. Even a single vulnerability can be exploited to access sensitive data, disrupt services, or compromise an entire cloud environment. Because of this heightened risk, securing REST APIs demands more than just addressing issues after deployment. It calls for a proactive, end-to-end approach that spans the full lifecycle—from design to deployment.
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 RESTful APIs are high-value targets for attackers
Their central role in modern application infrastructure makes APIs one of the most—if not the most—targeted components for attacks. RESTful APIs are especially attractive to attackers because:
They are often public-facing: REST API endpoints are generally exposed to the internet to support web applications, mobile apps, third-party integrations, and client-side interactions. This makes them easy for attackers to discover, scan, and target.
They follow predictable patterns: REST APIs typically use standardized URL structures and HTTP methods (e.g., GET, POST, PUT, DELETE), making them easier to map and probe using automated tools like fuzzers and scanners.
They handle sensitive data: APIs are prime targets for data exfiltration, considering they frequently transmit or expose personally identifiable information (PII), customer records, business logic, and internal data.
They are central to microservices: In modern distributed systems, REST APIs serve as communication bridges between services. This interconnectedness increases the blast radius of a successful attack, as a compromised API can affect multiple components.
They are vulnerable to development shortcuts: Agile workflows and fast-moving CI/CD pipelines usually prioritize rapid delivery over thorough security. As a result, vulnerabilities can make their way into production. Compounding the problem, most traditional application security testing tools—like static analysis (SAST) and dynamic scanning (DAST)—are not well-suited for detecting API-specific issues such as broken object-level authorization (BOLA) or excessive data exposure.
Common REST API security risks: The OWASP API Top 10
The REST API development landscape is built on established standards. But when these aren’t properly implemented, they lead to common, well-documented security risks. Most of these issues are covered by the OWASP API Top 10, the industry benchmark for API security.
Here’s a summary of the REST API vulnerabilities from that list you should watch out for:
Broken object-level authorization (BOLA)
Broken object-level authorization (BOLA) happens when a REST API lets a user read or modify an object when they shouldn't have the permissions to do so. This security issue can result in data disclosure, loss, or corruption.
Broken authentication
Broken authentication occurs when procedures for verifying user identity are poorly implemented, such as when they…
Permit credential stuffing
Fail to validate token authenticity
Accept unsigned, weakly signed, or expired JWT tokens
Store plain-text passwords in a database or rely on weak hashing algorithms
Attackers can exploit these flaws to pretend to be other users, including administrators.
Broken function-level authorization (BFLA)
Broken function-level authorization (BFLA) occurs when an API endpoint allows a user to access server-side functions via endpoints they shouldn’t be authorized to use. This vulnerability can lead to unauthorized operations, manipulation of system resources, and privilege escalation.
Broken object property-level authorization (BOPLA)
Broken object property-level authorization (BOPLA) occurs when a REST API allows a user to access, add, modify, or delete specific properties of an object they shouldn’t be authorized to. This often happens, for example, when there’s no proper query validation in GraphQL queries. Such flaws can lead to unauthorized exposure or manipulation of sensitive data within objects.
Unrestricted resource consumption
REST API requests consume resources like network bandwidth, CPU, memory, and disk space. Plus, some endpoints rely on API integrations that incur costs per request, like sending emails, SMS, or performing biometric validations. Without proper limits on how users can access REST APIs, you leave the door open to brute-force attacks, credential stuffing, and web scraping.
Unrestricted access to sensitive business flows
Some REST APIs implement critical business flows. If these endpoints are not properly protected, attackers could gain unrestricted access and cause direct harm to your business. One example? A threat actor could analyze your public APIs to identify key flows and automate requests to exploit them.
Server-side request forgery (SSRF)
Server-side request forgery (SSRF) vulnerabilities occur when an API fetches external resources using user-supplied URLs without proper validation. This flaw allows attackers to manipulate the backend into sending crafted requests to unintended targets, potentially exposing internal systems or triggering unwanted actions on third-party services.
Security misconfigurations
Security misconfigurations refer to several REST API security vulnerabilities, such as exposed debug endpoints, overly permissive CORS or CSP policies, missing TLS encryption, or absent cache-control directives. As a whole, these security misconfigurations weaken API defenses and increase the risk of exploitation through a wide range of attacks.
Improper inventory management
Improper API inventory management can leave some APIs undocumented, outdated, or forgotten but still active in production. These “shadow” API endpoints often lack proper security controls or depend on deprecated mechanisms, creating hidden attack surfaces that can be exploited without detection.
Unsafe consumption of APIs
Unsafe consumption of APIs happens because most endpoints need to connect to external endpoints to achieve their goals. The problem? Developers frequently place undue trust in third-party APIs, especially those from well-known providers. That overconfidence can result in weaker security practices like:
Failing to properly validate and sanitize incoming data
Trusting data transmitted over unencrypted channels
Not enforcing timeouts when calling external services
These oversights can expose your backend to security challenges if a third-party API is compromised or doesn’t behave as expected.
Watch 5-min 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
REST API security best practices
Below are some of the most effective API security best practices for RESTful backends:
| Specific API vulnerability | Best practice | API security category |
|---|---|---|
| Missing or weak token validation | Validate tokens on every request | Improper authentication |
| Weak function or role access control | Use RBAC for access control | BFLA / BOLA |
| Lack of fine-grained field access | Use ABAC or fine-grained policies for property-level control | BOPLA |
| Long-lived or poorly scoped tokens | Enforce short token lifespans and avoid never-expiring tokens | Improper authentication |
| Missing multi-factor authentication | Require 2FA/MFA for sensitive endpoints | Improper authentication |
| Insufficient protection on business flows | Enforce strict auth on critical business endpoints | Unrestricted access to sensitive business flows |
| No credential stuffing protection | Monitor login attempts | Improper authentication |
| Excessive data exposure | Return only necessary data | Unrestricted access to sensitive business flows |
| Data interception risk | Encrypt data in transit and at rest | Security misconfigurations |
| Unsanitized URLs in server requests | Validate and sanitize user-supplied URLs | SSRF |
| Leaking internal details in errors | Remove stack traces and verbose errors | General |
| Excessive or abusive API usage | Enforce strict rate limits | Unrestricted resource consumption |
| Rate-limiting bypass via IP rotation | Use stable user IDs for rate-limiting rules | Unrestricted resource consumption |
| Rate-limit header exposure | Hide rate-limit headers to prevent info leakage | Unrestricted resource consumption |
| Lack of perimeter protection | Use a WAF to block abusive traffic | Unrestricted resource consumption |
| API misconfiguration during development | Integrate API security tools into development workflow | Security misconfigurations |
| Lack of early vulnerability detection | Use security linters and SAST tools | Security misconfigurations |
| Insufficient API testing | Conduct manual or automated security tests | Security misconfigurations |
| Undocumented or forgotten APIs | Maintain API docs and inventory | Improper inventory management |
| Unmonitored third-party API performance | Monitor third-party API behavior | Unsafe consumption of APIs |
| Unsafe third-party data handling | Validate and encode data from third parties | Unsafe consumption of APIs |
| No traffic and endpoint monitoring | Analyze API gateway logs for anomalies | General |
| Poor incident response readiness | Maintain clear incident response runbooks | General |
Practical tips
Authentication and authorization
Validate tokens on each request and employ a standard authorization workflow like OAuth 2.0.
To prevent BFLA and reduce BOLA risks, implement strong access-control mechanisms like role-based access control (RBAC).
To limit BOPLA, adopt attribute-based access control (ABAC) or fine-grained policy enforcement.
Avoid never-expiring tokens and enforce short token lifespans to combat long-lived or poorly scoped tokens.
Require two-factor or multi-factor authentication (2FA/MFA) for sensitive or business-critical endpoints to minimize the risk of privilege escalation.
Enforce strict authentication and authorization practices on all critical business flow endpoints to ensure only legitimate users and roles can access them.
To defend against credential stuffing, monitor authentication attempts and introduce CAPTCHAs or progressive backoffs after repeated authentication failures.
Data protection
Instead of returning entire data objects, selectively expose only the necessary properties—ideally by implementing clear data transfer object (DTO) patterns or response schemas.
Protect against data interception by encrypting all data in transit and at rest using up-to-date cryptographic standards, such as TLS 1.3 and AES-256.
Validate and sanitize all user-supplied URLs or hostnames before any server-side requests to reduce SSRF risks.
Avoid leaking internal implementation details by removing stack traces, debug information, and overly verbose error messages from API responses.
Rate limiting and abuse prevention
Mitigate brute-force, DoS, DDoS, and scraping attacks by enforcing strict rate limits within your REST API backend at the application level.
Prevent rate-limiting bypass by using stable identifiers like JWT user IDs instead of IP addresses, which can be rotated via web proxies.
Reduce API endpoint saturation risks by configuring rate-limiting libraries not to expose standard rate limit headers, which attackers can use to fine-tune their request volume across multiple machines.
Strengthen perimeter protection by placing your REST API backend behind a Web Application Firewall (WAF) that detects and blocks abusive traffic or requests from untrusted IPs.
Secure design and development
Reduce misconfiguration risks by integrating both proprietary and open-source API security tools into the software development life cycle.
Detect issues early by configuring security linters directly in the IDE and integrating SAST tools into your API development workflow.
Perform periodic manual or automated API security testing to uncover hidden vulnerabilities and evaluate how well your REST endpoints withstand realistic attack scenarios.
Operational controls
Minimize shadow API risks by maintaining accurate API documentation via OpenAPI, keeping an up-to-date inventory based on cloud hosting resources, and listing all endpoints with tools like Spring Boot Actuator.
Minimize the impact of third-party API issues by continuously logging and monitoring external providers’ for performance drops or unexpected behavior.
Protect against unsafe API consumption by enforcing strict input validation and output encoding when handling data from third-party sources.
Analyze API gateway logs to track active endpoints and monitor incoming traffic patterns for anomalies or unauthorized access attempts.
Keep operational security tight by defining and maintaining clear runbooks and response procedures for REST API security incidents.
Shift left: Securing REST APIs in development
Catching REST API security vulnerabilities during development is cheaper, easier, and less risky than addressing them in production. That’s the essence of the shift-left approach to security, which involves:
Validating OpenAPI specs early: Scan API definitions to detect missing authentication requirements, incorrect use of status codes, overly generous response schemas, and overly detailed error messages.
Enforcing guardrails with policy as code: Utilize tools that support policy as code. like Open Policy Agent (OPA), to restrict allowed HTTP methods on a given endpoint, blocking insecure setups before deployment.
Identifying insecure configurations early: Integrate shift-left tools directly into the IDE and CI/CD pipeline to automatically flag missing API security headers, overly permissive settings, and other misconfigurations.
Testing and monitoring REST APIs for security gaps
Security teams should validate the security posture of REST APIs throughout their entire lifecycle by adopting a multi-layered approach:
Design: Leverage an open-source tool like Spectral to automatically examine OpenAPI definitions for security issues before development begins.
Development: Conduct secure code reviews, adopt security linters, and carry out static analysis with SAST scanners to spot vulnerabilities and flaws in the API source code.
Pre-deployment: Employ dynamic application security testing (DAST) tools to actively test running APIs for runtime issues that static analysis can’t detect, like broken authentication/authorization flaws.
Post-deployment: Take advantage of cloud security posture management (CSPM) and application performance monitoring (APM) tools to continuously monitor deployed APIs for anomalous access patterns, unusual traffic spikes, and attack attempts.
Remember: The last phase is particularly useful because post-deployment techniques are the only effective way to detect and stop all real-world attacks that may have escaped earlier testing phases.
How Wiz helps secure REST APIs
As we’ve seen, APIs are the primary gateways to cloud-native applications, which makes REST API security essential. After all, a single vulnerability in an exposed endpoint can put your entire cloud infrastructure at risk.
To defend against the onslaught of API vulnerabilities and misconfigurations, you need a holistic approach to security. That becomes far more manageable with a unified platform like Wiz, which secures applications from code to the cloud.
Wiz offers specialized capabilities for API security, including Wiz API security posture management (API-SPM), which automatically discovers and inventories APIs and leverages the Dynamic Scanner for API risk assessment. The Dynamic Scanner validates externally exposed APIs and tests them for security vulnerabilities and misconfigurations, enabling you to uncover potential attack paths.
Wiz helps you gain visibility into all of your APIs and proactively manage their security posture so you can minimize risk from REST APIs and other API types, including SOAP, GraphQL, and gRPC. Explore more by scheduling a demo.
Secure APIs from code to cloud
Learn how Wiz Code scans IaC, containers, and pipelines to stop misconfigurations and vulnerabilities before they hit your cloud.
