Preventing API attacks: Essential security best practices every developer should know

An API, or Application Programming Interface, is a set of rules, protocols, and tools that allows different software applications to communicate and interact with each other. It acts as a facilitator that lets software programs exchange data and functionality without delving into each other’s complex inner workings. By defining the methods and data formats, APIs simplify how developers request and share information across various systems, services, or components, improving integration and functionality.

APIs serve as the backbone of modern software development, commonly used in web development to enable communication between a web application and external services, such as social media platforms, payment gateways, or databases. They are the glue that integrates modular, reusable components, and third-party services into applications, playing a crucial role in composable architectures.

However, in a world where no information is completely secure from hackers, APIs are lucrative targets for attackers. They act like treasure maps, guiding malicious actors straight to an organization’s most valuable data. In fact, API attacks more than doubled within the past 12 months, with 37% of respondents experiencing an incident, compared to just 17% in 2023.

What is an API attack?

APIs can be vulnerable to various threats, including automated ones like bot attacks, abuse, or access violations. These attacks can lead to the loss of sensitive information, service interruptions, and significant data breaches. An API attack can occur in several forms, such as:

• Exploiting technical vulnerabilities, 
• Using stolen credentials for account takeover, or 
• Committing business logic abuse, which allows unauthorized manipulation of APIs in unexpected ways.

All types of APIs—internal, partner, and open—can have potential security vulnerabilities. Internal APIs are intended for internal use only but can still be targeted by hackers. Partner APIs, designed for collaboration between trusted parties, can also be vulnerable to attacks. Open APIs, which are exposed to the internet and meant for public use, constitute nearly 90% of all web traffic. However, they frequently contain an organization’s most guarded assets and become primary targets for attackers, thus exposing systems to security risks. Public APIs typically come with documentation about their structure and ways of implementation, which can inadvertently aid threat actors in launching their attacks.

Exploring different types of API attacks and their prevention techniques

APIs are vulnerable to a variety of attacks, which are thoroughly categorized and detailed in the OWASP API Security Top 10 list. Here are a few key ones we will focus on.

Broken object level authorization 

Broken object level authorization (BOLA), also known as insecure direct object references (IDOR), strikes when an application fails to enforce access restrictions on resources. This vulnerability allows attackers to manipulate object references in requests to access unauthorized data. This vulnerability arises when an application relies solely on user-supplied input such as IDs or keys to determine which resources a user can access, without proper validation or authorization checks. 

How to prevent it

Preventing IDOR vulnerabilities demands a comprehensive strategy. Developers must first establish robust access controls and authorization mechanisms at both the application and server levels. Key actions include validating user permissions and ensuring that each request is authorized to access specific resources. It is vital to avoid exposing sensitive data directly in URLs or other parameters that can be easily manipulated. 

Broken authentication

Broken Authentication is a critical security vulnerability that occurs when an application’s authentication mechanisms are improperly implemented, allowing attackers to compromise user accounts or gain unauthorized access to sensitive data or functionality.

Exploiting Broken Authentication vulnerabilities can take various forms. For instance, attackers might attempt to brute-force login credentials by repeatedly guessing usernames and passwords until they find a valid combination. Alternatively, they could exploit weaknesses in session management to hijack active user sessions or bypass authentication altogether. Other attack vectors include credential stuffing, where attackers use lists of stolen usernames and passwords from other breaches to gain unauthorized access to accounts on the target application.

How to prevent it

Preventing Broken Authentication vulnerabilities requires implementing robust security measures throughout the authentication process. Developers should enforce strong password policies, and proper session management practices should be followed. These practices include using secure, randomly generated session identifiers, implementing session timeouts, and enforcing the use of HTTPS. Adding multi-factor authentication (MFA) can further enhance security by requiring additional verification.

Excessive data exposure

Excessive Data Exposure occurs when systems unintentionally leak sensitive information to unauthorized users or attackers. This leakage can result from various factors, including inadequate access controls, improper configuration of security settings, or unintentional disclosure through error messages or debugging endpoints.

Attackers may exploit these vulnerabilities to access sensitive information, which can then be used for identity theft, fraud, or other malicious purposes. For example, consider a scenario where a web application displays detailed error messages that include database query information or stack traces. An attacker could use this information to gain insights into the application’s underlying structure and potentially exploit vulnerabilities to access or manipulate sensitive data stored in the database.

How to prevent it

To prevent excessive data exposure, developers must sanitize error messages, restrict access to sensitive information, implement proper authentication and authorization mechanisms, and use data encryption or obfuscation to protect data both in transit and at rest.

Injection attacks

Injection attacks, such as SQL injection (SQLi) and cross-site scripting (XSS), pose significant threats to APIs by allowing attackers to inject malicious code or commands into input fields or parameters. These attacks can lead to data breaches, data manipulation, or the execution of arbitrary code on the server.

Consider an API endpoint that accepts user-supplied input to construct database queries. If the input is not properly sanitized or validated, an attacker could inject malicious SQL code into the request, potentially gaining unauthorized access to the database or manipulating its contents.

How to prevent it

To combat injection attacks, developers must employ parameterized queries and robust input validation techniques to shield against malicious code. Additionally, deploying web application firewalls (WAFs) and conducting regular vulnerability audits are crucial steps in identifying and mitigating potential security weaknesses.

Rate limiting and denial of service (DoS) attacks

Rate limiting and Denial of Service (DoS) attacks target APIs by overwhelming them with a high volume of requests, leading to service degradation or outage. Attackers may exploit APIs that lack rate-limiting controls or are vulnerable to brute force attacks, disrupting access for legitimate users.

For example, an attacker could launch a brute force attack against an API endpoint that lacks rate-limiting controls by sending a large number of authentication requests in rapid succession to guess valid credentials and gain unauthorized access.

How to prevent it

To mitigate the risk of rate limiting and DoS attacks, developers should implement rate-limiting controls to restrict the number of requests that can be made within a specified timeframe. Additionally, deploying distributed denial of service (DDoS) mitigation techniques and monitoring API traffic for suspicious activity can help identify and counter DoS attacks.

Conclusion 

APIs are a strategic necessity, providing the agility, innovation, and speed crucial for success in today’s rapidly evolving market. As they support modern software development, protecting APIs against security threats becomes paramount. Despite 80% of attack attempts leveraging one or more of the top 10 methods outlined on OWASP’s list, only 58% of organizations prioritize protection against these threats. By understanding common API hacks and implementing robust security measures, developers and organizations can safeguard their APIs and the data they manage from unauthorized access, exploitation, and disruption. By prioritizing security throughout the development lifecycle and remaining vigilant against emerging threats, organizations can maintain the integrity, availability, and confidentiality of their APIs. Contact our team for expert guidance and implement proven security strategies to defend against API threats.