API Security

“An unsecured API is literally an ‘all you can eat buffet’ for hackers.”

What is API security?

API security is the protection of network-exposed APIs that an organization, both owns and uses. APIs are becoming the preferred method to develop new-age applications. They are one of most common ways to interact between microservices and containers like systems and apps. API are developed using REST or SOAP methods. However, the true strength of API security depends on how there are implemented.

REST API Security Vs SOAP API Security

REST APIs use HTTP and Support Transport Layer Security Encryption (TLS). It is a standard that makes the connection private and checks whether the data transferred between the two systems (client and server) is encrypted. REST API is faster than SOAP because of the statelessness of nature. REST API doesn’t need to store or repackage data.

SOAP APIs use built protocols known as Web services. These protocols are defined using a rule set that is guided by confidentiality and authentication. SOAP API has not been around for as long as REST API. SOAP API is more secure than REST API as it uses Web security for transmission long with SSL.

Why is API security important?

Organizations use API to connect services and transferred data. The major data breaches through API are broken, exposed, or hacked APIs. The way API security is used depends on what kind of data is transferred.

Security testing of APIs is currently a challenge for 35% of organizations, that need better capabilities than what current DAST and SAST technologies offer to automatically discover APIs and conduct testing. Organizations are moving from monolithic web applications to modern applications such as those that make heavy use of client-side JavaScript or ones that utilize microservices architecture.

How API Security works?

API security depends on authentication and authorization. Authentication is the first step; it is used to verify that the client application has the required permission to use API. Authorization is the subsequent step that determines what data and action an authentication application can access while interacting with API.

APIs should be developed with protective features to reduce the system’s vulnerability to malicious attacks during API calls.

The developer is responsible for ensuring the developed API successfully validates all the input collected from the user during API calls. The prepared statements with blind variables are one of the most effective ways to prevent API from SQL injection. XSS can be easily handled by cleaning the user input from the API call. Cleaning the inputs helps to ensure that potential XSS vulnerabilities are minimized.   

Best Practice for Secure API

Some basic security practice and well-established security control if the APIs are shared publicly are as follows:

• Prioritize security: Potential loss for the organization happens using unsecured APIs, so make security a priority and build the API securely as they are being developed.
• Encrypt traffic using TLS: Some organizations may choose not to encrypt API payload data that is considered to be non-sensitive, but for organizations whose API exchange sensitive data, TLS encryption should be essential.
• Validate input: Never pass input from an API through to the endpoint without validating it first.
• Use a WAP: Ensure that it can understand API payloads.
• Use token: Establish trusted identities and then control access to services and resources by using tokens.
• Use an API gateway: API gateways act as the major point of enforcement for API traffic. A good gateway will allow you to authenticate traffic as well as control and analyze how your APIs are used.

Modern API Data breach

USPS Cooperate Database Exposure

The weakness allowed an attacker to query the USPS website and scrape a database of over 60 million cooperate users, email addresses, phone numbers, account numbers, etc.

Exploitation

The issue was authentication-related which allowed unauthorized access to an API service called ‘informed visibility’, which was designed to deliver real-time tracking data for large-scale shipping operations.

This tracking system was tied into web API in a way that users could change the search parameters and view and even in some cases modify the information of other users. Since there wasn’t a robust anti-scraping system in place, this mass exposure was compounded by the automated and unfettered access available.

Lessons Learned

Providers giving extreme power to a specific service or function without securing every permutation of its interaction flow can lead to such exploits. To mitigate API-related risks, coding should be done with the assumption that the APIs might be abused by both internal and external forces.

References:

1. https://www.redhat.com/en/topics/security/api-security
2. https://searchapparchitecture.techtarget.com/definition/API-security
3. https://nordicapis.com/5-major-modern-api-data-breaches-and-what-we-can-learn-from-them/

About the Author –

Logaiswar is a security enthusiast with core interest in Application & cloud security. He is part of the SOC DevSecOps vertical at GAVS supporting critical customer engagements.