Identifying error codes and messages

In this section, we are going to learn about error codes and messages that can be provided by API endpoints when they are answering your requests. Error codes and messages are the cornerstones of effective API penetration testing. They act as a window into the API’s communication channels, revealing how they inform clients and users about issues encountered during request processing. By deciphering these messages, you can assess the strength and security of the API’s error-handling mechanisms. Scrutinizing error responses can expose potential security vulnerabilities such as information leaks, injection attacks, or weak input validation.

One obvious approach to uncover error codes and messages is by checking the API documentation. In Chapter 3, you learned about the importance of this stage of pentesting. Another approach is manual testing. Here, pentesters craft requests with deliberately malformed data or incorrect inputs, observing...