Modern digital systems operate through the hidden structure of APIs which serve as their fundamental connection mechanism. The system enables banking operations and healthcare services through its connection of applications and devices and cloud-based platforms. The ability to connect different systems through APIs reveals potential security risks. Attackers can use vulnerable APIs to gain unauthorized access which results in data theft and financial damage and system breakdown.
The complete API Security Guide & Checklist provides detailed instructions for building secure APIs. The document provides essential information about queries such as how to secure an API , what are the security principles, threats and practical examples for developing secure APIs that meet compliance standards.
What is API Security?
API security refers to the complete set of methods and instruments which defend Application Programming Interfaces against unauthorized usage and data theft and improper usage. The system protects sensitive information through secure operations while restricting access to authorized clients who need to use the API functions. API security protects the fundamental elements of confidentiality and integrity and availability which form the foundation of all cybersecurity systems. The system implements robust authentication systems and authorization controls and encryption protocols and monitoring tools to stop data exposure and injection-based attacks.
Why is API Security Important?
APIs reveal essential business operations together with organizational information to outside systems through their interfaces. The structured nature of APIs makes them attractive targets for cyber attackers. A vulnerable API endpoint can lead to complete application security breaches. Organizations must follow regulatory requirements which include GDPR and HIPAA and PCI-DSS standards for protecting sensitive data. The growing number of API connections in cloud-native and microservice environments creates multiple security vulnerabilities because each connection represents a potential risk.
What Is the Difference Between API Security and App Security?
| Aspect | API Security | Application Security |
| Scope | Focuses on securing endpoints and data exchange between systems | Focuses on protecting the user-facing application and its logic |
| Primary Concern | Authentication, authorization, encryption, and input validation | Code security, user sessions, and interface vulnerabilities |
| Common Threats | Injection attacks, token theft, data exposure, rate abuse | Cross-site scripting, session hijacking, data tampering |
| Data Handling | Ensures secure transmission and storage of data through APIs | Ensures secure interaction and input validation on the front-end |
| Architecture | Often stateless and token-driven | Can be session-based or browser-dependent |
What are the Key Threats to API Security?
Attackers take advantage of the weaknesses and improper configurations of authentication systems. They then execute these broken authentication attacks. Attackers try to obtain or guess authentication tokens so that they can use them to mimic authorized users and easily evade any security measures.
When APIs that accept user-input permissions without proper verification become vulnerable to such attacks. Here any users can get unauthorized access to data and operational capabilities through Broken Authorization vulnerabilities.
Injection Attacks:
Attackers use specially designed commands to modify database queries and exploit backend systems such as SQL, NoSQL, XML. They manipulate server-based codes and data for attacks. APIs disclose too much information through their data exposure because of insufficient filtering mechanisms. This can also lead to accidental exposure of personal data and financial information as well as internal organizational details.
Rate Abuse:
Unrestricted requests can cause performance issues or complete denial of services for genuine users. Automated scripts and bots with no limits can overload servers which results in service issues that affect all users who need access to the system.
Security Misconfiguration:
Developers at times store API credentials in code repositories and configuration files. In case these aren’t protected it can be easily accessible to attackers. If default settings or unnecessary features are left enabled attackers can use them to expose admin panels, open ports and discover valuable information.
Server-Side Request Forgery (SSRF):
Attackers can trick APIs to make internal requests. This vulnerable API allows attackers to access private networks or any other sensitive information through crafted URLs.
Unvalidated Input:
If the inputs are not properly validated, it can cause data manipulation or buffer overflows. The acceptance of unverified input data allows attackers to manipulate attacks and trigger system crashes. As logging and monitoring is missing, attackers can remain undetected until their actions result in major system damage.
API Security Checklist: Comprehensive Set of Measures to Protect Application Programming Interfaces
Here are the different API security checklist to understand – How to secure an API.
Authentication and Authorization:
Use token-based authentication (like OAuth 2.0, OIDC, or JWT) to verify users and systems.
Always give users or services only the access they actually need — nothing more.
Check permissions and authentication on every incoming request.
Regularly perform token rotation and revocation to keep access secure.
Data Protection:
Make sure all endpoints use HTTPS/TLS — no unsecured connections.
Encrypt data both in storage and during transmission.
Disable outdated TLS versions and weak cipher suites.
For internal APIs, use mutual TLS or VPNs to add an extra layer of security.
Input Validation and Output Encoding:
Authenticate all input fields and parameters against expected patterns.
Implement rigorous checks for JSON and XML payloads.
For filtering inputs use a trusted list.
To prevent injection and XSS attacks, neutralize all outputs.
Rate Limiting and Throttling:
To prevent abuse, set request limits per user or IP.
For unusually high traffic enable automatic throttling .
Differentiate between suspicious activity and legitimate high traffic .
Error Handling & Information Leakage
Do not reveal internal details and Use standardized error messages .
Never show stack traces or server information to users.
To define security events and errors use HTTP status codes consistently
Logging and Monitoring:
NIncluding status codes log all requests and responses
Capture user identity, IP addresses, and timestamps
Watch for anomalous or suspicious behavior patterns
Integrate with SIEM tools for real-time threat detection and alerts.
API Gateway and Firewall:
Use an API Gateway as the central control and monitoring point.
Deploy a Web Application Firewall (WAF) to block common attacks
Scan incoming and outgoing traffic for malicious data.
Handle SSL termination and authentication at the gateway.
Secrets Management:
Always store API keys in a secure vault, never store in codes.
Update and Rotate credentials regularly.
Use environment variables or secure parameter stores for sensitive data.
Monitoring & Auditing:
Conduct regular log reviews to detect unusual access.
Track configuration changes and deployments
Set up alerts for unauthorized access or suspicious behavior
Regular Testing & Updates:
Include API security testing and penetration testing in routine checks.
Automate testing within your CI/CD pipelines.
Fix vulnerabilities and update dependencies promptly.
Deactivate and remove unused or outdated API endpoints.
What are the Most Common Vulnerabilities in API Security?
- APIs become vulnerable to internal design errors which developers fail to detect during their development process. The following security weaknesses frequently appear in API systems:
- The absence of validation between user identity and data ownership in BOLA attacks enables attackers to access unauthorized records and confidential resources belonging to other users.
- The absence of proper restrictions on hidden or admin endpoints enables attackers to perform unauthorized actions through privilege escalation.
- Attackers use mass assignment techniques to modify object properties through payload manipulation of internal field names which should remain hidden from API exposure.
- The system reveals excessive sensitive information because it fails to perform adequate filtering and shares complete internal object attributes through API responses.
- The absence of proper input filtering creates security vulnerabilities which allow attackers to perform injection attacks and data corruption that leads to backend SQL and NoSQL and command-based exploits.
- Unlimited resource usage through uncontrolled traffic flow causes denial of service because it overloads the server which results in performance degradation and system unavailability.
- Security misconfigurations such as default credentials, open ports, or verbose error messages expose valuable system details that attackers can easily exploit.
- The extended duration of tokens without expiration creates security risks because it enables attackers to perform replay attacks and steal tokens which results in sustained unauthorized system access.
- The absence of audit trails makes it impossible to track incidents and identify responsible parties which extends the time needed to detect security breaches.
How to Build a Secure API Development Lifecycle?
Design Phase:
The project needs to establish rules for authentication and authorization and data protection procedures. The team needs to perform threat modelling to analyze both endpoints and data transmission paths. The team should use OpenAPI to document APIs while performing schema validation.
Development Phase:
The development team needs to follow secure coding standards during their work. The system requires API key management and vault-based secrets storage for integration. The system requires built-in logging functionality together with rate limiting and access control mechanisms.
Testing Phase:
The testing process includes both static and dynamic code analysis tools. The testing process includes penetration testing and fuzz testing as part of its protocol. The system needs to check its business rules for potential security vulnerabilities and exploitation attempts.
Deployment Phase:
The API needs to operate through an API gateway or firewall during its deployment stage. The system requires TLS encryption together with certificate management systems. The system requires rate limits and alert systems and performance metrics for operation.
Maintenance Phase:
The system requires scheduled credential updates to occur at regular intervals. The system requires ongoing security monitoring and audit procedures. The system requires periodic updates of its dependencies and security patches. These security steps need to be integrated into the API development process to maintain continuous protection throughout its entire life cycle.
What are the Key Use Cases for API Protection?
Protecting Sensitive Data
APIs need to protect sensitive information because they process financial data and personal information and healthcare records which require both encryption and secure access controls.
Ensuring Regulatory Compliance
The system must follow GDPR and HIPAA regulations by implementing authentication protocols and logging functions and consent management systems.
Securing Against Malicious Attacks
The system protects itself from malicious attacks through input validation and throttling mechanisms which defend against injection and enumeration and DDoS attacks.
Managing Access and Identity
The system requires OAuth2 and OIDC and custom RBAC/ABAC frameworks to manage user access securely.
Supporting Modern Architectures
The system enables secure communication between microservices and containers and cloud-based environments.
Improving Operational Visibility
Real-time abuse detection and anomaly identification becomes possible through operational visibility improvements achieved by monitoring and tracing and analytics tools.
OWASP API Security Top 10 Checklist:
API1 – Broken Object Level Authorization: Enforce access control for every object.
API2 – Broken Authentication: Use secure token and credential handling.
API3 – Broken Object Property Level Authorization: Limit exposure of sensitive fields.
API4 – Unrestricted Resource Consumption: Apply strict rate limits.
API5 – Broken Function Level Authorization: Separate user and admin functions.
API6 – Unrestricted Access to Sensitive Business Functions: Restrict privileged operations.
API7 – Security Misconfiguration: Secure all defaults and disable debug modes.
API8 – Mass Assignment: Whitelist allowed fields only.
API9 – Improper Inventory Management: Maintain up-to-date API inventories.
API10 – Unsafe Consumption of APIs: Validate all external and internal API calls.
How DoveRunner Protects Your APIs and Applications?
The mobile application security system of DoveRunner defends APIs and applications through multiple protection layers. The system implements Runtime Application Self-Protection (RASP) to identify and stop unauthorized attempts to modify or debug or reverse engineer applications in real-time. The system protects API keys and user information through AES-256 encryption and secure key management systems. The system performs device integrity verification to stop access from rooted or emulated devices because it prevents fake clients from using APIs. The zero-code integration feature of DoveRunner enables fast protection deployment for Android and iOS applications. The system tracks ongoing threats and generates analytical reports to show attempted attacks while maintaining full compliance with GDPR and PCI DSS and HIPAA regulations.
Why Mobile App Security is Now a Non-Negotiable Requirement:
The annual occurrence of billions of malware events leads to massive cleanup expenses and permanent damage to corporate brands. Your mobile applications need to fulfil worldwide regulatory requirements (GDPR, HIPAA, RBI, SEBI) while working smoothly with current API systems and development platforms.
The mobile application protection solution from DoveRunner exists to fulfil this specific requirement.
Leading-Edge Features for Total Protection
The solution enables protection deployment through a zero-coding process which preserves your development workflow so you can build apps while DoveRunner protects them.
The system provides immediate protection against both known and unknown security threats which emerge as zero-day.
The system provides real-time protection through RASP which identifies attempts to tamper with or debug or intercept network traffic to preserve application integrity during attacks.
The system enables smooth integration with Jenkins and TeamCity CI/CD platforms and Crashlytics crash analytics tools which maintain security performance without delays.
Platform-Specific Modules
The system provides continuous protection for Android mobile applications across all OS versions without needing external servers. The system supports CLI tools which enable you to integrate security features into your build pipeline.
The system provides enhanced SDK-based security features for iOS applications which include built-in jailbreak detection and offline functionality and automated build system integration.
The system provides AES-256 and FIPS 140-2 compliant encryption for API key protection and sensitive data security and PCI DSS and HIPAA and GDPR compliance.
The on-premise security deployment option provides complete infrastructure control to regulated industries which need data localization and cloud service independence.
Digital transformation depends on APIs which function as both its central component and its most vulnerable point in today’s connected environment. API security requires more than best practices because it has become an essential requirement for modern digital operations. API security demands a systematic approach which starts with the design phase and continues through authentication and data protection and monitoring and auditing stages. Technical security measures including encryption and rate limiting should be implemented alongside governance procedures that handle key rotation and compliance verification and audit activities.
DoveRunner develops a security ecosystem through advanced encryption and intelligent threat detection and continuous monitoring which provides adaptive protection against modern threats. The security system protects API interactions through performance optimization and scalability enhancement and extended system reliability.
Frequently Asked Questions:
How to Secure REST API?
- Enforce HTTPS for all endpoints.
- Use token-based authentication (JWT, OAuth2).
- Validate user input and apply rate limiting.
- Log requests and monitor anomalies.
- Rotate API keys and revoke old tokens.
How to Secure REST API Using Spring Security?
- Use spring-boot-starter-security for authentication layers.
- Implement JWT or OAuth2-based authorization filters.
- Disable sessions for stateless APIs.
- Restrict endpoints using roles and scopes.
- Protect headers, handle exceptions, and apply CSRF protection if required.
How to Know If Your API is Secure?
- TLS enforced on all endpoints.
- Strong authentication and role-based access control.
- Logs and alerts for unusual activity.
- Regular penetration and compliance tests.
- No sensitive data in responses or URLs.
What is API Security Testing?
API security testing checks APIs for vulnerabilities and misconfigurations. It includes:
- Static code analysis.
- Dynamic and fuzz testing.
- Authentication/authorization validation.
- Injection and rate-limit testing.
- Logic flow analysis.
How to Test API Security?
- Identify all endpoints and access patterns.
- Test authentication tokens and privileges.
- Inject malformed requests to observe handling.
- Check rate limits, error messages, and response codes.
- Audit logs and alerts after simulated attacks.
What are the API Security Requirements for Fintech and Healthcare?
- End-to-end encryption of all data.
- Multi-factor authentication for clients.
- Fine-grained authorization for sensitive records.
- Strict audit logs and traceability.
- Compliance with PCI-DSS, HIPAA, or PSD2.
Why API Security Matters for Fintech Mobile Apps?
APIs power every transaction and data request. Weak APIs can lead to financial theft or identity fraud. Proper API security ensures user trust, compliance, and operational resilience.
How to Secure API Key in Android App?
- Avoid embedding API keys in source code.
- Use encrypted Android Keystore or secure backend proxy.
- Implement short-lived tokens.
- Use certificate pinning and key obfuscation.
- Rotate and monitor key usage.
What are the Best Practices for API Key Management?
- Issue unique keys per client.
- Limit scopes and permissions.
- Store in vaults, not hardcoded.
- Rotate keys frequently.
- Monitor logs for anomalies.
How to Prevent API Hacking and Injection Attacks?
- Validate inputs with strict schemas.
- Use parameterized queries.
- Encode outputs.
- Apply firewall and intrusion detection systems.
- Limit payload sizes and request rates.
What are the Best Practices for an API Security Audit?
- Perform comprehensive vulnerability scans.
- Conduct manual code and logic reviews.
- Validate access control and key rotation policies.
- Simulate attacks and record responses.
- Document risks and remediate promptly.
