Intro to API Security

API security explained

Many organizations provide customers with access to their data through an application programming interface (API), enabling them to build customized solutions or enhance services. However, this access introduces security risks, making API security an essential component of any business's success.

What is API security?

API security refers to the strategies and measures put in place to protect data confidentiality, integrity, and availability within APIs. These measures include:

• Authentication and authorization: Implementing mechanisms that ensure only authorized users and applications can access the API. Authentication confirms the user’s identity, while authorization determines their level of access.
• Data protection: Using encryption to protect data in transit and at rest. Secure communication protocols, such as HTTPS and TLS, prevent interception or tampering with data exchanged through APIs.
• Monitoring and logging: Tracking API usage to detect and respond to potential security threats. Monitoring unusual traffic patterns, such as an excessive number of requests, can help detect malicious activity early.
• Testing and vulnerability assessments: Conducting regular testing, including penetration tests, vulnerability scans, and code reviews, to identify weaknesses before they can be exploited by attackers.

Why is API security important?

Without robust API security, organizations are vulnerable to a range of attacks that can have severe repercussions. API vulnerabilities can be exploited by attackers to access sensitive data, such as personal information, financial records, and login credentials. Such breaches can lead to identity theft, fraud, and cybercrime. Attackers may also execute denial-of-service (DoS) attacks, preventing users from accessing essential services.

For businesses that rely on APIs to interact with third-party services, a security breach can result in:

• Reputational damage: Loss of customer trust.
• Financial loss: Costs associated with breach response and potential loss of business.
• Legal repercussions: Fines, regulatory penalties, and potential lawsuits due to non-compliance with data protection regulations.

How to enhance API security

1. Implement rate limiting and throttling: Limit the number of requests a user can make in a given timeframe to prevent abuse.

2. Use API gateways: Gateways provide a central control point to manage, monitor, and secure API traffic.

3. Adopt a zero-trust model: Zero Trust requires all users and systems, even those inside the network, to verify their identity.

4. Educate developers: Ensure that API developers understand secure coding practices and regularly update their skills to keep up with evolving threats.

API security vs. application Security

Though API security and application security often overlap in discussions, they serve different purposes in securing digital environments. API security is essential for protecting data shared between systems and devices, while application security focuses on safeguarding the end-user experience and data within software applications.

Key differences

1. Attack surface:

• APIs generally have a larger attack surface than traditional web applications, as they are designed to connect with a wide range of clients, which inherently introduces more vulnerability points.
• Applications, especially web applications, usually have a more limited attack surface since they often interact directly with end-users rather than other systems.

2. Accessibility and vulnerability:

• APIs are accessible by multiple platforms and devices, making them more susceptible to security threats. Their open accessibility for integration purposes can lead to exploitation if not properly secured.
• Applications, by contrast, are designed with a user interface in mind, with security threats often centering around user input handling, session management, and UI vulnerabilities.

3. Authentication schemes:

• APIs frequently use token-based authentication mechanisms like OAuth and JSON Web Tokens (JWT), allowing clients to authenticate via tokens instead of traditional credentials.
• Web applications commonly employ two-factor authentication (2FA) methods, such as sending a verification code to a user’s smartphone in addition to password entry, to verify identity.

4. Top security risks:

• The OWASP Top 10 for APIs includes authorization flaws at the object and function levels, as well as issues related to excessive data exposure.
• The OWASP Top 10 for Web Applications, however, focuses more on user interface (UI) flaws, session management vulnerabilities, and issues arising from insecure UI components.

Essential API security standards

When developing secure APIs, adhering to key standards related to encryption, authentication, and authorization is essential.

1. TLS encryption:

Transport Layer Security (TLS) is a protocol that secures connections between the client and server by encrypting data in transit. This prevents data interception or tampering by third parties and is critical for securing sensitive information during transfer.

2. OAuth:

OAuth is an authorization framework that grants third-party applications limited access to an API without sharing the main credentials. OAuth creates a temporary token, allowing controlled access to resources for a specific time frame without compromising security.

3. SAML (Security Assertion Markup Language):

SAML, an XML-based standard, is widely used for secure authentication and authorization exchanges. It’s commonly implemented in Single Sign-On (SSO) systems, allowing users to authenticate once and access multiple applications securely without needing to re-enter credentials.

4. JWT (JSON Web Token):

JWT is a compact, URL-friendly token format used to represent authentication and authorization claims. A JWT contains essential details, such as user ID and expiration time, in a secure and efficient way, making it ideal for session management and authorization in web and mobile apps.

5. OWASP REST Security cheat sheet:

OWASP REST Security cheat sheet offers guidelines to protect REST APIs from common vulnerabilities, including injection attacks, broken authentication, and data exposure. Among its recommendations is the use of JWT for managing user authentication and securing data transmission.

Top 10 API security issues and how to prevent them

APIs are essential for enabling communication between applications, but they come with their own set of security challenges. The OWASP Top 10 API Security Issues highlight the most common threats APIs face today, primarily focusing on authorization and access control vulnerabilities. Here’s a closer look at these issues and recommended best practices to prevent them.

How are APIs exploited in the wild?

1. Broken object-level authorization

Broken object-level authorization occurs when an API fails to verify whether a user has access to specific objects, enabling attackers to access or alter restricted data. Preventing this risk requires a centralized access control mechanism that enforces object-level authorization consistently across the application. This mechanism should accurately verify user permissions for each object request, helping to prevent unauthorized access.

2. Broken user authentication

Broken user authentication happens when APIs do not adequately authenticate users, allowing attackers to impersonate legitimate users. To prevent this, implement multi-factor authentication (MFA) and secure password storage practices, such as hashing and salting passwords. MFA strengthens security by requiring users to verify their identity through additional devices or credentials, reducing the risk of impersonation.

3. Broken object property-level authorization

In APIs that handle large objects, there’s a risk of exposing unnecessary data through object properties, even if object-level access is secure. Limiting data exposure through encryption and data filtering is essential to address this risk. Encrypt sensitive properties within objects and carefully filter data before returning it to clients, ensuring that only the necessary information is accessible.

4. Lack of resources and rate limiting

When APIs lack resource management or rate-limiting controls, they become vulnerable to denial-of-service (DoS) attacks. To prevent this, enforce rate limiting to control the number of requests users can send and implement resource allocation mechanisms to ensure fair usage. This strategy limits excessive requests, preserving API performance and availability.

5. Broken function-level authorization

Broken function-level authorization arises when APIs do not enforce authorization at the function or endpoint level, giving attackers unintended access to restricted functions. A centralized access control mechanism should manage function-level authorization, enforcing policies for every endpoint. This helps limit access to sensitive functions based on user roles.

6. Server-side request forgery (SSRF)

SSRF occurs when an API accepts URLs from clients without validating them, allowing attackers to send malicious URLs that expose internal services. To prevent SSRF, use URL allowlists that restrict requests to approved URLs and filter internal IP addresses to prevent unauthorized access to internal resources.

7. Security misconfiguration

Security misconfiguration happens when APIs use insecure settings or outdated software, making them vulnerable to attacks. Mitigate this by following secure coding practices and using secure defaults. Regularly update software, disable unnecessary features, and employ hardened configurations to minimize exposure to potential attacks.

8. Lack of protection from automated threats

Automated attacks, such as bots exploiting business workflows, can cause financial losses or damage an organization’s reputation. Protect against these threats by implementing device fingerprinting and blocking suspicious IP addresses, such as Tor exit nodes. Additionally, impose reasonable usage limits on key flows (e.g., purchasing or referrals) and require proof of personhood for high-risk transactions.

9. Improper asset management

Improper management of assets, such as  keys and certificates, can lead to unauthorized access. Use secure coding practices and regularly update security configurations to prevent this issue. Disable unnecessary features, employ secure defaults, and regularly review asset permissions to minimize risks from unauthorized access.

10. Unsafe consumption of third-party APIs

APIs often rely on third-party APIs, which may have their own security weaknesses. Sanitize all inputs (including data from third-party APIs) to prevent injection attacks, and use allowlists for hostnames to restrict potential vulnerabilities. These steps help control access and reduce the risk of data exposure from unsafe third-party API interactions.

Keep your APIs secure

Managing API security can seem complex, but it doesn’t have to be. The CrowdStrike Falcon® platform assesses your API security posture across multiple hosts, keeping an eye on your service configurations and helping to test for potential threats. With CrowdStrike Threat Graph®, cloud-scale AI analyzes API events in real time.

Try the Falcon platform today to enrich your endpoint and workload telemetry with actionable security insights.