SQL Injection Blind (The Basic Knowledge)

Blind SQL Injection is used when a web application is vulnerable to an SQL injection but the results of the injection are not visible to the attacker. The page with the vulnerability may not be one that displays data but will display differently depending on the results of a logical statement injected into the legitimate SQL statement called for that page. This type of attack can become time-intensive because a new statement must be crafted for each bit recovered. There are several tools that can automate these attacks once the location of the vulnerability and the target information has been established.^[11]

[edit] Conditional responses

One type of blind SQL injection forces the database to evaluate a logical statement on an ordinary application screen.

SELECT booktitle FROM booklist WHERE bookId = 'OOk14cd' AND '1'='1';

will result in a normal page while

SELECT booktitle FROM booklist WHERE bookId = 'OOk14cd' AND '1'='2';

will likely give a different result if the page is vulnerable to a SQL injection. An injection like this may suggest to the attacker that a blind SQL injection is possible, leaving the attacker to devise statements that evaluate to true or false depending on the contents of another column or table outside of the SELECT statement's column list.^[12]

SELECT 1/0 FROM users WHERE username='ooo';