What Is API Security?
API security is the use of any security practice relating to application programming interfaces (APIs), which are common in modern applications. API security involves managing API privacy and access control and the identification and remediation of attacks on APIs. These attacks exploit API vulnerabilities or reverse engineer APIs.
APIs help developers to build client-side applications, which target employees, partners, consumers and the like. The client-side of an application (such as a web application or a mobile application) interacts with the server-side via an API. APIs are also central to microservices architectures.
APIs are typically available through public networks (accessed via any location), making them easily accessible to attackers, and they are well-documented, making them simple to reverse-engineer. This makes APIs a natural target for cybercriminals, and they are especially sensitive to Denial of Service (DoS) attacks.
A cyber attack commonly involves side-stepping the client-side application in an effort to disrupt the workings of an application for other users or to obtain private data. API security focuses on securing this application layer and attending to what may happen if a cybercriminal were to interact directly with the API.
In this article you will learn about the following API security best practices:
Common API Security Risks and Attacks
1. Stay Current with Security Risks
2. Encrypt Your Data
3. Identify API Vulnerabilities
4. Eliminate Confidential Information
5. Apply Rate Limits
6. Validate API Inputs
7. Apply an API Security Gateway
8. Build Threat Models
9. Use API Firewalls
10. Use OAuth and OpenID Connect
11. Automate API Security Testing with Bright
Common API Security Risks and Attacks
Understanding the common API security risks and attacks is the first step towards implementing API security best practices. Let’s discuss some of these threats in detail.
Injection Attacks
An injection attack occurs when an attacker sends malicious data to an API, tricking it into executing unintended commands. For example, an attacker might send a SQL query that deletes data from a database as part of an API request. Injection attacks can result in data breaches, data loss, or even complete system takeover.
Broken Authentication
Broken authentication attacks happen when an attacker is able to impersonate a legitimate user by exploiting weaknesses in the API’s authentication mechanism. This could involve stealing user credentials, session tokens, or exploiting vulnerabilities in the authentication protocol itself. Once inside, the attacker can perform any action the impersonated user is authorized to do.
Insecure Direct Object References (IDOR)
Insecure Direct Object References (IDOR) occur when an API exposes direct references to internal resources. An attacker can manipulate these references to gain unauthorized access to data. For example, if an API uses sequential numbers as identifiers for user profiles, an attacker might guess the number of another user’s profile to access their data.
Exposure of Sensitive Information
Exposure of sensitive information is a common API security risk. It occurs when an API unnecessarily reveals sensitive information, like user passwords or credit card numbers, in its responses. This can happen due to poor coding practices or lack of proper data sanitization procedures.
Lack of Rate Limiting
Rate limiting is a technique used to control the number of requests a client can send to an API in a certain period. If an API lacks proper rate limiting, it may be susceptible to DoS (Denial of Service) attacks or brute-force attacks.
Misconfigured CORS (Cross-Origin Resource Sharing)
Cross-Origin Resource Sharing (CORS) is a mechanism that allows many resources (e.g., fonts, JavaScript, etc.) on a web page to be requested from another domain outside the domain from which the resource originated. Misconfigured CORS can allow unauthorized domains to make requests, potentially leading to data breaches.
API Versioning
API versioning refers to the practice of having multiple versions of an API to accommodate changes in its structure or functionality over time. If not managed properly, API versioning can lead to security risks. For instance, deprecated versions of the API might still be accessible and lack the security enhancements of newer versions.
Now that we have reviewed some of the most common security threats, letās dive into best practices that can help you improve API security.
1. Stay Current with Security Risks
One of the most critical aspects of API security is staying informed about the latest threats and vulnerabilities. This includes regularly consulting resources such as OWASP (Open Web Application Security Project) API Security Top Ten, security blogs, and industry news. Additionally, it’s essential to participate in security forums and mailing lists to stay informed about the latest trends and best practices in the field of API security.
It is also important to ensure that your software and APIs are always up-to-date. This includes applying security patches, updating libraries, and upgrading to the latest version of the platforms you are using. Outdated software is more vulnerable to attacks, so it’s crucial to keep everything current to minimize the risk of a security breach.
Having a well-defined security policy is vital to ensure that all team members are aware of the best practices and guidelines for API security. This policy should cover various aspects such as authentication, authorization, data protection, and monitoring. Additionally, it should be regularly reviewed and updated to reflect the latest security trends and best practices.
Related content: Read our guide to API security testing
2. Encrypt Your Data
Encrypting your data is one of the most critical steps in ensuring API security. One way to do this is by using HTTPS (Hypertext Transfer Protocol Secure) and TLS (Transport Layer Security) to secure the communication between client and server. HTTPS and TLS help protect sensitive information from being intercepted, modified, or stolen by attackers.
It is also essential to protect data at rest. This includes encrypting data stored in databases, file systems, or other storage systems. Various encryption techniques can be used, such as transparent data encryption, column-level encryption, or file-level encryption. By encrypting data at rest, you can prevent unauthorized access and data breaches in case your storage systems are compromised.
When using encryption, it’s crucial to have a robust key management strategy in place. This includes generating, storing, and managing encryption keys securely. Ensure that encryption keys are stored separately from the encrypted data and access to the keys is restricted to authorized personnel only. Additionally, you should regularly rotate encryption keys to minimize the risk of compromise.
3. Identify API Vulnerabilities
To identify vulnerabilities in your APIs, it’s essential to perform regular security audits. These audits should include a thorough examination of your API architecture, design, and implementation. Ensure that you check for common vulnerabilities such as injection flaws, broken authentication, and insecure data storage. Regular security audits help you identify potential weaknesses in your APIs and address them before they can be exploited by attackers.
Continuous monitoring is another essential aspect of identifying API vulnerabilities. This includes monitoring your APIs for unusual activity, performance issues, and potential security threats. By implementing continuous monitoring, you can detect and respond to security incidents more quickly and efficiently.
4. Eliminate Confidential Information
One of the best ways to protect confidential information is to avoid storing sensitive data in your APIs altogether. This includes data such as passwords, access tokens, and API keys. Instead, use secure methods like token-based authentication and OAuth to grant access to your APIs.
If you must store sensitive data, it’s essential to use data masking techniques to obfuscate the information. Data masking can help protect sensitive information by replacing it with random or fictitious data, making it harder for attackers to gain access to the actual data. This is particularly useful when dealing with personally identifiable information (PII) or other sensitive information that should not be exposed.
Another aspect of eliminating confidential information is implementing proper access controls. This includes using role-based access control (RBAC) or attribute-based access control (ABAC) to restrict access to sensitive data and API endpoints. By limiting access to the data and functionality of your APIs, you can prevent unauthorized access and protect sensitive information from being exposed.
5. Apply Rate Limits
Rate limiting helps prevent API abuse and denial of service (DoS) attacks. By limiting the number of requests that can be made to your API within a specific time frame, you can ensure that your APIs remain available for legitimate users while preventing attackers from overwhelming your system with a flood of requests.
In addition to rate limiting, you can also implement API quotas to restrict the number of requests that can be made by a single user, application, or IP address. This can help protect your APIs from abuse and ensure that your resources are allocated fairly among your users.
Adaptive rate limiting is a more advanced technique that involves dynamically adjusting the rate limits based on factors such as user behavior, traffic patterns, and resource usage. This can help you provide a better user experience while still protecting your APIs from potential threats.
6. Validate API Inputs
To ensure the security of your APIs, it’s essential to validate all input data before processing it. This includes checking for data types, lengths, formats, and allowed values. By validating input data, you can prevent various security vulnerabilities such as injection attacks and buffer overflows.
Another crucial aspect of checking API parameters is sanitizing output data. This includes removing any potentially harmful content, such as HTML, JavaScript, or SQL code, from the data returned by your APIs. By sanitizing output data, you can protect your users and applications from potential cross-site scripting (XSS) and other code injection attacks.
When working with databases, it’s essential to use parameterized queries and prepared statements to prevent SQL injection attacks. By using these techniques, you can ensure that user input is treated as data rather than executable code, making it more difficult for attackers to inject malicious SQL code into your queries.
7. Use an API Security Gateway
An API security gateway is a specialized software or hardware solution that helps protect your APIs from external threats. By acting as a proxy between your API and the client, an API security gateway can enforce security policies, authenticate and authorize users, and monitor API traffic for potential threats.
By implementing security features at the gateway level, you can offload some of the security responsibilities from your API, making it more scalable and easier to manage. Some common security features provided by API security gateways include authentication, authorization, rate limiting, and encryption.
API security gateways can also help you monitor and log API traffic, allowing you to analyze patterns and detect potential security incidents. By collecting and analyzing logs, you can gain insights into your API usage, identify potential security issues, and improve the overall security of your APIs.
8. Build Threat Models
Threat modeling is a process used to identify potential threats and vulnerabilities in your APIs. By understanding the possible risks and attack vectors, you can develop appropriate countermeasures and security controls to protect your APIs.
To build effective threat models, it’s essential to analyze the various components of your APIs, such as endpoints, data stores, and communication channels. Additionally, you should examine the data flows between these components to understand how data is processed, stored, and transmitted.
Based on the identified threats and vulnerabilities, you can develop appropriate security controls and countermeasures to mitigate the risks. These controls may include encryption, access controls, input validation, and monitoring. By implementing these security measures, you can help protect your APIs from potential attacks and breaches.
9. Use API Firewalls
API firewalls are specialized security solutions that help protect your APIs from malicious traffic. By filtering incoming requests based on predefined rules and policies, API firewalls can block potential attacks and prevent unauthorized access to your APIs.
Using access control lists (ACLs), you can define the rules and policies that determine which clients are allowed to access your APIs. This can help you restrict access to specific IP addresses, users, or applications, ensuring that only legitimate users can access your APIs.
API firewalls can also help you monitor and analyze API traffic, allowing you to detect potential security incidents and respond more quickly. By collecting and analyzing logs, you can gain insights into your API usage, identify potential security issues, and improve the overall security of your APIs.
10. Use OAuth and OpenID Connect
OAuth and OpenID Connect are widely used standards for securing authentication and authorization in APIs. OAuth provides a secure way for clients to access protected resources on behalf of users, while OpenID Connect enables user authentication and single sign-on (SSO) across multiple applications.
By using token-based authentication, you can ensure that your APIs are protected from unauthorized access. OAuth and OpenID Connect use access tokens and ID tokens, respectively, to grant access to your APIs. These tokens are short-lived and can be revoked or refreshed as needed, providing a more secure alternative to traditional username/password authentication.
OAuth and OpenID Connect allow you to leverage existing identity providers (IdPs) such as Google, Facebook, or Azure Active Directory for authentication and authorization. By using these services, you can offload the management of user accounts and credentials, making it easier to maintain and secure your APIs.
11. Test Your APIs with Dynamic Application Security Testing (DAST)
Dynamic Application Security Testing (DAST) is a technique used to identify security vulnerabilities in running applications. By interacting with your APIs and analyzing the responses, DAST tools can help you detect potential issues such as broken authentication, insecure data storage, and cross-site scripting (XSS) attacks.
By integrating DAST into your development and deployment pipelines, you can automate security testing and ensure that your APIs are continuously monitored for potential vulnerabilities. This can help you catch security issues early on and save time and resources by fixing them before deployment.
API Testing with Bright Security
Bright has been built from the ground up with a dev first approach to test your web applications, with a specific focus on API security testing tools.
With support for a wide range of API architectures, test your legacy and modern applications, including REST API, SOAP, and GraphQL testing.
Bright complements DevOps and CI/CD processes, empowering developers to detect and fix vulnerabilities on every build. It reduces the reliance on manual testing by leveraging multiple discovery methods:
- HAR files
- OpenAPI (Swagger) files
- Postman Collections
Start detecting the technical OWASP API Top 10 and more, seamlessly integrated across your pipelines via:
- Bright Rest API
- Convenient CLI for developers
- Common DevOps tools like CircleCI, Jenkins, JIRA, GitHub, Azure DevOps, and more
