What are API vulnerabilities?
Application programming interfaces (APIs) enable communication between services, applications, and data systems—powering everything from mobile apps to large-scale enterprise platforms.
But this power comes at a cost. APIs have rapidly become a prime target for attackers, with vulnerabilities in their design, implementation, or configuration creating serious risks for organizations.
Unlike traditional web apps, APIs offer direct access to sensitive operations and data, often without the same user-facing safeguards. This makes them prime targets for malicious actors to conduct:
Data exfiltration: Transferring PII, credentials, financial, or other sensitive data without authorization
Business logic abuse: Manipulating flows like pricing, permissions, or transactions
Access control bypass: Gaining unauthorized access to protected data
Advanced API Security Best Practices [Cheat Sheet]
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Common Causes of API Vulnerabilities
Several recurring issues are behind most API flaws:
Insecure access controls: Even with token-based auth, APIs may skip critical authorization checks, exposing sensitive operations.
Poor input validation: Without strict input validation, attackers can inject unexpected or malicious data—leading to injection flaws, logic bypasses, or system crashes.
Shadow APIs: APIs are created quickly, often without centralized tracking, leaving overlooked endpoints (shadow APIs) in production unnoticed; these create blind spots and increase exposure risk.
This article explores why APIs are uniquely challenging, how to detect and prioritize them, and how to prevent them in modern development environments. We’ll also examine how platforms like Wiz offer a context-rich approach to managing API risk effectively.
API Governance: Best Practices & Solutions
API governance refers to the policies, standards, and processes that guide how APIs are built, managed, and secured.
Read more
Why APIs Are Hard to Secure
Securing APIs demands a different mindset than traditional application security. Many tools and strategies built for web apps fall short when applied to APIs—primarily because APIs are consumed and behave differently.
APIs differ from web apps in a few key ways:
Machine-to-machine interaction: APIs are consumed by services, not humans—no browser or UI means bypassing traditional defenses is easier.
Token-based authentication: Unlike web apps that rely on sessions and cookies, APIs rely on bearer tokens (OAuth2, mTLS), often with minimal session handling.
Deeper exposure of backend logic: APIs directly expose functions like payment processing, account management, and data export. Without proper restrictions, attackers can perform unauthorized operations more easily than through a UI.
Cloud-native complexity
Modern development practices (microservices, containers, serverless computing) significantly increase API overgrowth.
Each service often exposes one or more APIs, and while environments like Kubernetes and AWS Lambda facilitate rapid deployment, they complicate visibility. APIs are also deployed and deprecated frequently, leading to outdated or forgotten endpoints.
Where Traditional Tools Fall Short
Solutions like WAFs and firewalls may not detect abuse in JSON payloads or GraphQL queries, while legacy scanners fail to detect undocumented/internal APIs. As developers deploy new versions quickly, security blind spots emerge, often without centralized oversight or standardized reviews.
Without purpose-built API security measures, organizations face the risk of silent, persistent exposure through endpoints they don’t even know exist.
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How to Detect API Vulnerabilities
Detecting API vulnerabilities effectively requires both proactive assessments and runtime observability. Modern strategies span across the development lifecycle, from code to production.
Specification analysis
Reviewing API specs (OpenAPI/Swagger) is key to finding early security gaps. It reveals misconfigurations, poor access controls, missing authentication, and loose parameters, all of which are potential vulnerabilities.
Static code analysis (SAST)
SAST tools examine source code early in development, identifying security flaws like missing authorization, hardcoded credentials, insecure data exposure, or reliance on user-controlled parameters. These tools are especially valuable during development or CI pipelines, enabling developers to catch issues before code moves to production.
Dynamic analysis (DAST) and fuzzing
These methods simulate real-world abuse by sending malformed or unexpected requests to APIs.
DAST tools can uncover issues like:
Input validation bypasses
Business logic flaws
Broken rate limiting
Fuzzing is a dynamic testing technique that sends malformed or unexpected inputs to APIs to uncover bugs, crashes, or security vulnerabilities. By introducing unpredictable and diverse inputs, fuzzing helps identify edge-case flaws that might otherwise go undetected during standard API security testing.
Runtime telemetry and behavioral monitoring
At runtime, it's critical to monitor how APIs are actually being used. Numerous anomalies can reveal real-time attacks or misuse that wouldn’t be visible from static analysis alone. These include:
Credential stuffing
Excessive requests from single IPs
Unusual sequences of API calls
Unauthorized data exports
Token abuse and rate limit monitoring
Even authenticated APIs are vulnerable if tokens are compromised, reused, or overly privileged. Monitoring token usage (frequency, source, scope) and enforcing granular rate limits can detect and contain abuse.
Why Context is Critical for Prioritization
Not every API vulnerability poses the same level of risk or urgency. A test endpoint in a dev environment may have the same technical flaw as a payment API in production, but the risk level is worlds apart.
Most vulnerability scanners simply report the presence of an issue, without answering:
Is this API exposed to the internet?
Is it connected to sensitive data (PII, credentials, financial info)?
Is it reachable by over-permissioned roles or external actors?
Is the endpoint live in production or a dormant dev instance?
Without this context, security teams struggle to focus on what's urgent, wasting time on noise while overlooking critical gaps.
Code-to-cloud visibility
To prioritize effectively, teams need code-to-cloud context, a unified view that ties together:
Identity and access: Who can invoke the API, and from where?
Data sensitivity: What kind of data does the API expose or interact with?
Deployment context: Is the API in a hardened production VPC or an open dev environment?
Wiz connects the dots between vulnerabilities, infrastructure, and identity. It reveals whether a vulnerable API is exposed, if it handles sensitive data, and whether it’s reachable by risky IAM roles.
How to Prevent API Vulnerabilities
Prevention is always better than detection. To build APIs that are secure by design, follow API security best practices to avoid common vulnerabilities.
Validate inputs strictly
Rely on strict schema validation to enforce data types, formats, length constraints, and parameter expectations. Every input—regardless of origin—should be treated as untrusted.
Strong authentication
Adopt mature standards like OAuth2 and mTLS to authenticate client-service communication. Use short-lived access tokens with tightly scoped permissions to limit the blast radius of token compromise. Also, regularly rotate tokens and revoke stale or unused credentials to maintain hygiene.
Enforce authorization everywhere
Always enforce authorization at the object level on the server side. Even authenticated users must be validated for each resource or operation. Never rely on client-side controls, as attackers can bypass front-end logic using direct API calls or automation tools.
Minimize data exposure
Only return the fields required for an operation. Internal implementation details (e.g., isAdmin, userId, database IDs) should be excluded unless absolutely necessary. Excess data increases the likelihood of leakage, user enumeration, or privilege escalation.
Apply rate limiting and anomaly detection
Throttle API access per user, IP, or token to limit the impact of automated attacks and abuse. Use behavioural analytics to monitor request patterns, detect anomalies such as spikes in traffic or unexpected access attempts, and flag potentially malicious behavior before it escalates.
Maintain an up-to-date API inventory
Continuously maintain a real-time inventory of all APIs – public, private, and internal. Use automated discovery to detect undocumented (shadow) APIs and deprecated endpoints, both of which are commonly overlooked and can silently introduce exposure in production environments.
How Wiz Supports API Security
Wiz takes a context-rich approach to API security that goes beyond basic detection. It helps security teams answer the critical question: Which API risks actually matter to our business?
Here’s how Wiz supports API security across the entire lifecycle:
Discovers all APIs – including shadow and internal: Wiz automatically scans cloud environments to surface known and unknown APIs, even those created by third parties or left undocumented in production.
Correlates vulnerabilities with real-world risk: It links API findings with cloud context – including sensitive data access, identity permissions, internet exposure, and network reachability – so teams can prioritize based on impact, not just technical severity.
Prioritizes what’s exploitable: Wiz surfaces the API risks that matter most by combining vulnerability insights with environment-specific factors like IAM role sprawl, misconfigurations, and public access paths.
Monitors behavior and enforces protection at runtime: By analyzing runtime activity, Wiz helps detect token abuse, excessive requests, and anomalous behavior – even on authenticated endpoints – giving teams a real-time view of API risk.
Connects code to cloud: With end-to-end visibility from development to production, Wiz ties API risks back to the source – whether in infrastructure, application code, or third-party services – enabling faster, more informed remediation.
Not all API vulnerabilities are equal. Get a demo to see how Wiz helps you prioritize what actually matters. →
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