API Security: REST vs. SOAP vs. GraphQL & 8 Best Practices

• Why is API Security Important?
• How is API Security Different from General Application Security?
• REST API Security vs. SOAP Security vs. GraphQL Security
• OWASP Top 10 API Security Threats

• Six Automated Threats to APIs
• Best Practices for API Security
• API Security with Radware

• Authentication and authorization: Implement token-based authentication methods, such as OAuth 2.0 or JSON Web Tokens (JWT). REST APIs often use HTTPS to encrypt data in transit.

• Input validation: Validate all inputs to prevent injection attacks. REST endpoints are often vulnerable to improper input handling.

• Rate limiting and throttling: Use rate-limiting strategies to mitigate DoS/DDoS attacks by controlling the number of requests per user or IP.

• Secure data handling: Avoid exposing sensitive information in URLs, as they are logged in browsers and servers. Use request headers or body for sensitive data transmission.

• WS-Security standards: SOAP supports WS-Security for message-level security, enabling features like XML encryption, signing, and token-based authentication.

• Transport Layer Security (TLS): SOAP APIs commonly use TLS to ensure secure communication.

• Complexity and granularity: The strict schema of SOAP provides detailed error handling but can expose vulnerabilities if the schema is improperly configured.

• Access control: Strong authentication and authorization mechanisms are essential, as SOAP APIs often integrate with critical business systems.

• Query complexity limiting: Monitor and restrict query depth and breadth to prevent resource exhaustion attacks, such as DoS through overly complex or nested queries.

• Authentication and authorization: Implement robust user authentication and field-level authorization to ensure only permitted data is accessible.

• Validation and sanitization: Validate all incoming queries to avoid injection attacks. Since GraphQL relies on dynamic query construction, improper handling can lead to vulnerabilities.

• Introspection restrictions: Disable introspection queries in production environments to limit attackers' visibility into the API structure.

API Abuse

Attackers reverse engineer mobile and web applications to hijack API calls, and program bots to invade the business APIs. They target APIs to take over accounts, scrape business-critical data and perform application distributed denial of service (DDoS) attacks. Bots deluge the API server with unwanted requests. It is essential to distinguish accurately between good API calls and bad API calls, for online businesses.

Vulnerabilities in APIs are abused by cybercriminals and nefarious parties to steal Personally Identifiable Information (PII) and business-critical data, carry out account takeover attacks and systematically execute website content scraping campaigns. The types of bot-executed API abuse attacks include application DDoS, account takeover and web scraping.

Application DDoS

APIs can be attacked by hackers and cybercriminals who intentionally overload APIs with large volumes of bot traffic from multiple devices and IP addresses. For enterprises, business-critical services are thus put at risk, such as login services, session management and other services that enable application uptime and availability for users.

Attackers who carry out DDoS campaigns often use asymmetrical techniques through which they send small volumes of data to generate API calls, which usually result in servers being heavily overloaded as they need to answer such API calls with much larger volumes of data. These attacks seriously tie up system resources, and greatly increase the server response times for all users of the system.

Credential Stuffing

Credential stuffing exploits users’ propensity to use the same username and password on multiple websites. Hackers use bots to test lists of credentials obtained as a result of data dumps of breached credentials (or purchased from the dark web), against a range of websites in the hope that a victim has used the same combination of credentials on multiple sites. Unlike credential cracking, credential stuffing does not involve brute force or guessing of any values; instead, mass login attempts are used to verify the stolen username and password pairs. Credential stuffing symptoms include consecutive login attempts with different credentials from the same HTTP client.

Credential Cracking or Brute Force

Also known as “brute forcing,” credential cracking is a way to identify valid credentials by trying different values for usernames and passwords (usually from lists of breached account credentials that were made public by malicious parties and hackers). Hackers deploy bots to hack into customers’ accounts using the brute force approach, dictionary attacks (inputting large numbers of words) and guessing attacks to identify valid login credentials. Brute force attack symptoms include a sudden increase in failed login attempts and high numbers of account hijacking complaints from customers.

Account Takeover

Account takeover (ATO) is a form of identity theft where a fraudster illegally uses bots to get access to a victim’s bank, e-commerce site or other types of accounts. A successful ATO attack leads to fraudulent transactions and unauthorized shopping from the victim’s compromised account. Fraudsters use two primary methods to hijack accounts: credential stuffing and credential cracking.

Web Scraping

Competitors, fraudsters, and fly-by-night operators who set up websites to defraud consumers often plagiarize an entire website’s content by carrying out systematic scraping campaigns, using bots to extract data from APIs. Hackers also try to reverse engineer web and mobile applications to hijack API calls and carry out scraping attacks.

Authentication ensures the identity of users or systems accessing the API, while authorization defines what actions they are permitted to perform. To secure APIs effectively, use robust mechanisms like OAuth 2.0 or OpenID Connect, which support secure token-based authentication and minimize the risks of credentials being compromised during transmission. For applications requiring heightened security, implement multifactor authentication (MFA), requiring users to validate their identity through multiple methods, such as passwords combined with biometrics or one-time passcodes.

Authorization should enforce granular access controls, applying role-based access control (RBAC) or attribute-based access control (ABAC). For example, a user with "read-only" permissions should not be able to perform write or delete actions. Additionally, segregate system-level and user-level access, ensuring API keys for backend services have distinct privileges separate from end-user tokens. By combining these measures, you reduce the likelihood of unauthorized actions being performed on your APIs.

Input validation is one of the most critical steps to ensure APIs do not process malicious or malformed data. For example, user-provided inputs, such as query parameters, headers, and request bodies, must be checked against strict rules. Ensure inputs conform to expected data types, lengths, formats, or allowed ranges. For example, if an API expects a numeric ID, reject any input containing non-numeric characters.

Sanitization further removes malicious content, especially in APIs that handle user-generated inputs. Escaping or encoding dangerous characters can prevent injection attacks, such as SQL injection or cross-site scripting (XSS). For APIs interacting with databases, always use parameterized queries to avoid direct embedding of user inputs into SQL statements. Validation libraries and frameworks can simplify enforcing these practices, ensuring consistency and reducing developer errors.

Rate limiting and throttling protect APIs from abuse by restricting the number of requests a client can make within a specified timeframe. This can prevent Denial of Service (DoS) attacks, where attackers flood the API with excessive requests, causing service degradation or downtime.

For example, set limits such as “100 requests per minute per user” and enforce them through API gateways or load balancers. Use algorithms like the token bucket or leaky bucket, which allow a steady request flow while permitting occasional bursts within defined limits. For more sensitive endpoints, such as those handling financial transactions, enforce stricter rate limits to prevent brute force or abuse attempts. Throttling can also help balance traffic loads, prioritizing genuine users while blocking malicious or high-frequency requests.

API endpoints are the primary points of interaction and are highly targeted by attackers. Start by encrypting all communications using HTTPS, which ensures that data exchanged between clients and servers cannot be intercepted or altered by attackers. Secure APIs by avoiding information leakage; for example, do not expose stack traces, server configurations, or other debug details in API responses.

Endpoints should also implement measures like IP whitelisting, where only specific IP addresses or ranges are permitted to access critical services. Utilize content security policies (CSPs) to prevent injection-based attacks. Furthermore, implement mechanisms to validate user sessions and tokens, ensuring requests come from legitimate sources. The use of strong TLS configurations and periodic certificate updates further fortifies endpoint security.

Monitoring and logging provide visibility into API usage and help detect anomalous behavior. Log details such as request origins, user identities, timestamps, and resource access patterns. Centralize logging data in a system compatible with Security Information and Event Management (SIEM) tools, enabling real-time analysis and alerting.

For example, suspicious activity such as repeated failed login attempts or unusually high traffic from a single IP address could indicate brute force attacks or DDoS attempts. Integrate monitoring solutions like Prometheus, ELK Stack, or Datadog to visualize API performance metrics, detect anomalies, and trigger automated responses to mitigate potential threats.

The principle of least privilege should govern API exposure. Only expose endpoints that are essential for the API’s functionality and restrict access to sensitive resources. Employ API gateways to enforce policies like geofencing, IP blacklisting, or rate limiting at the network level. For APIs that handle sensitive operations, implement additional security measures, such as requiring elevated permissions or re-authentication for access.

Deprecate older API versions that no longer meet security standards. For instance, an API version relying on outdated encryption protocols should be retired promptly to avoid exploitation. Maintain clear documentation about API endpoints and their intended use cases to help developers avoid accidental misuse or exposure of critical functions.

Security testing ensures that vulnerabilities are identified and remediated before APIs are deployed to production. Use tools like Burp Suite, OWASP ZAP, and Postman to perform static application security testing (SAST) and dynamic application security testing (DAST). Fuzz testing, which involves sending random or invalid data to APIs, can help identify unexpected behaviors or crashes that attackers could exploit.

Regularly schedule penetration tests to simulate real-world attacks and uncover hidden vulnerabilities. Pair automated tests with manual code reviews for critical areas, ensuring security measures are correctly implemented. Maintain an incident response plan to address vulnerabilities quickly if discovered in live APIs.

APIs are frequent targets of bots and Distributed Denial of Service (DDoS) attacks, which can disrupt services, degrade performance, and compromise data. Anti-DDoS solutions mitigate these threats by filtering malicious traffic and enforcing rate-limiting policies that cap the number of requests from a single source. Cloud-based services can absorb and distribute massive attack traffic across global networks, ensuring uptime during high-traffic events. Layered defense mechanisms address threats at the network and application layers, blocking volumetric floods like SYN floods and application-layer attacks like Slowloris.

Bot management solutions differentiate legitimate users from automated threats through behavioral analysis, CAPTCHA challenges, and device fingerprinting. Advanced tools detect patterns typical of bots, such as repetitive or high-speed requests, and use IP reputation databases to block known attackers. Honeypots and decoys attract malicious bots, enabling their isolation without affecting genuine traffic. Combining anti-DDoS services with bot detection and mitigation strategies ensures a comprehensive defense, maintaining API performance and availability while reducing the impact of malicious automation.