How to Avoid API Data Leaks

Discover best practices for securing your APIs and preventing data breaches. Prioritize API management, be stingy with data, and stay up to date with the latest security practices.

Ann Marie Bond Ann Marie Bond

With the shift from monolithic applications to microservices and cloud computing, APIs are now commonplace. They help facilitate communication between multiple applications, services, and end users and have revolutionized how web applications are built.  

However, while APIs have helped accelerate innovations in the digital landscape, they can expose the critical application business logic and sensitive data that malicious actors often target. As such, they provide an exploitable attack surface susceptible to anyone looking to access and manipulate valuable data within a system. 

The nature of APIs makes it difficult to stop all attacks, as any vulnerabilities in the API can potentially lead to data breaches or other types of cyber-attacks. Moreover, their thorough documentation renders them easy to reverse-engineer. However, following some best practices can help you mitigate API security risks.

Stop API data leaks

More companies are relying heavily on APIs to fuel their business innovations, making API security a key priority. However, preventing data leaks can be challenging due to the increasing complexity of API systems designed to support a wide variety of clients and devices. This makes it challenging to implement consistent security measures across the API ecosystem.  

Furthermore, there are many avenues for attacks, so an incomplete understanding of API attack surfaces leaves many API vulnerabilities exposed. Organizations that lack sufficient awareness of their API attack surfaces struggle to reduce data leaks. With the constantly evolving nature of cyber threats and the rise of new vulnerabilities and attack methods, it isn’t just the scale and complexity of the API’s ecosystem creating challenges. Perhaps the biggest problem is that most organizations think of security as an afterthought and try eliminating API security threats using tools that can’t automatically discover API vulnerabilities.

What causes API leaks?

There are many security risks in API design and attackers use various methods to exploit these vulnerabilities. One of the most common methods is broken access. This occurs when attackers gain unauthorized access to an API’s resources, allowing them to view or modify data without permission.  

Unauthorized access can also enable bad actors to use distributed denial-of-service (DDoS) attacks to overwhelm a server with API with requests, causing it to crash or become unresponsive. 

Another popular cause of API data exploits is SQL injection. In this data breach, attackers inject malicious code into an API, usually through a web application, to gain access to sensitive information. Some sophisticated attacks use valid API tokens or keys to exploit any vulnerability in the business logic of an API system to access the data layer.  

An additional cause of data breaches is excessive data exposure, whereby more data than necessary is unintentionally available to users or the public. This vulnerability differs from data breaches like SQL injections because it doesn’t require malicious code to take advantage of the system. Instead, it results from security negligence that allows unauthorized parties to view more information than is needed in a request’s response.

Best practices for data protection

Cyber threats are constantly evolving, making it crucial to strengthen your API security. Data protection in any application or API system is a complex process that involves implementing multiple layers of security controls and measures. Considering the increasing amount of data collected, stored, and shared, it’s important to understand that no single method can guarantee complete data protection. 

There isn’t any “one size fits all” method for protecting data in an API system because the security measures depend on the nature and scale of the data protected, the types of threats organizations face, and the resources available to implement these security controls. Understanding that the different types of data you’re collecting and storing require different types of protection is essential to address the risks associated with each type of data. For example, how you secure financial data might differ from how you protect personal data.  

Organizations should assess their security needs carefully and implement a combination of security measures, such as encryption, authentication, and validation policies and procedures, to ensure they protect data throughout the lifecycle of an API system. 

Think security first

Every step of the API design process should consider security and include robust testing for vulnerabilities at each step. This testing should account for vulnerabilities like SQL injection, cross-site scripting, cross-site request forgery, and authorization and authentication policy enforcement.  

Many companies lack the in-house expertise to assess and secure their APIs properly. So, it’s best practice to rely on third-party security experts who can use tools like penetration testing to identify and fix possible vulnerabilities that in-house teams may not detect. Additionally, a third-party expert or service can help ensure the policies are properly enforced and provide guidance on the best practices for secure API design. 

API product managers responsible for the requirements and functionality of APIs should also ensure that key nonfunctional requirements, such as security, are included in the API design process. By prioritizing security in the product’s roadmap, API product managers can ensure the confidentiality, integrity, and availability of data transmitted through APIs.

Monitor everything

Monitoring an API involves tracking all activities that occur within it, including requests, responses, and errors. Monitoring an API is a critical security measure for any application or system as it helps to identify and prevent a wide range of issues, including security vulnerabilities, data breaches, performance issues, and even bugs. It provides key insights into usage patterns and performance, allowing you to identify and block any suspicious activity, such as unauthorized requests or suspicious responses.  

Some examples of monitoring an API include logging at the application level, real user monitoring and analytics, or using distributed tracing tools. Because no API is immune to attacks, monitoring everything is necessary to stay up to date with the latest security threats and make informed decisions about your API’s security.  

Moreover, smart monitoring is vital to handle the amount of data effectively. This involves using context-aware tools (some with artificial intelligence or machine learning) to proactively monitor, detect, and alert users to potential issues with their APIs. It may include a combination of real-time monitoring and alerts, historical data and analytics, integration with other tools and systems, customizable rules and thresholds for alerts, and automated testing and debugging capabilities.

Be stingy with data

It’s important to be frugal with data when designing APIs to ensure that it’s secure and protected. When users or clients request data, you can improve your API’s security and privacy by returning the minimum data required.  

Designing your APIs to be stingy reduces security risks by eliminating any extra data that attackers could use to gain access to sensitive information. If the data returned is unnecessary, you shouldn’t include it in the API. This adds an extra layer of security.

Prioritize API management

With the increasing use of APIs comes the need for a sophisticated system dedicated to keeping your APIs organized and monitored. It’s easy for APIs to become disorganized and vulnerable to attack without proper management to secure them. 

Prioritizing API management is also essential to ensure you have the tools, features, and services that make it easy to use and manage APIs with monitoring, analytics, testing, and security measures like API gateways and policy enforcement. 

Having a sophisticated API management system also allows businesses to easily keep track of all their APIs, better understand how their APIs are used and by whom, and provide the visibility to help optimize their APIs’ performance.

Stay up to date

It’s essential to stay aware of the current API security threats and best practices to mitigate them to protect your organization. This can include regularly reviewing your API security policies and conducting regular security assessments to ensure that your API is secure and compliant with industry standards. Additionally, you should subscribe to vulnerability alerts, database exploits, and security advisories such as Exploit Database, CVE List, and Google Security blog

Using third-party security tools is also beneficial to stay up to date. These tools can provide you with real-time monitoring and alerting, vulnerability assessments, and other security-related services that can help you quickly identify and fix potential vulnerabilities before attackers exploit them. They may include cyber security tools that can perform penetration testing, encryption, detect packet sniffers, scan web vulnerabilities, conduct post-deployment scans, and detect network intrusions.


APIs have revolutionized how web applications are built and used, but they can also expose sensitive data and critical application business logic, which malicious actors often target. This makes API security a key priority for protecting your API from data leaks and ensuring the integrity of your systems and applications. 

Some of these best practices for protecting your API from data leaks include having a security-first approach when designing your APIs, monitoring everything in the API system, being stingy with data, prioritizing API management tools, and staying up to date with security best practices. Additionally, it’s essential to regularly review your API security policies and update them as needed.  

Check out Software AG to learn more about preventing data breaches in your APIs.