SQL injection UNION attack, determining the number of columns returned by the query
Let's filter for Accessories.
Since we are proxying the traffic through Burp Suite, we can go to the Proxy > HTTP History tab to view this request.
Let's forward this request to the Repeater for further modification.
Once in the Repeater, let's set the category parameter to the following:
UNION SELECT NULL--
Since the application returns an error, we know that the number of columns in the current query is more than 1.
Let's try for two columns:
UNION SELECT NULL,NULL--
The application again returns an error.
Let's try for three columns:
UNION SELECT NULL,NULL,NULL--
The application no longer throws an error which means that there are 3 columns in the current query.
We have solved the lab.