When a web application uses a URL parameter like id to retrieve data from a database, it often uses a SQL query like this:

$query = "SELECT * FROM users WHERE id = '1' OR 1=1 --"; This query will return all rows from the users table, allowing the attacker to access sensitive data.

http://example.com/php?id=1' upd In this example, an attacker is attempting to inject malicious SQL code by adding a single quote ( ' ) and the upd keyword to the id parameter.

The inurl:php?id=1 and upd vulnerability is a type of SQL injection attack that targets web applications using PHP and a database management system such as MySQL. The attack involves manipulating the id parameter in a URL to inject malicious SQL code.