Seven Deadliest Web Application Attacks

Inference

Some SQL injection vulnerabilities cannot be detected by direct observation of errors. These vulnerabilities require an inference-based methodology that compares how the site responds to a collection of specially crafted requests. This technique is also referred to as blind SQL injection.

An inference-based approach attempts to modify a query so that it will produce a binary response, such as forcing a query to become true or false, return one record or all records, or respond immediately or respond after a delay. This requires at least two requests to determine the presence of a vulnerability. For example, an attack to test true and false in a query might use OR 17=17 to represent always true and OR 17=37 to represent false. The ...