Blind SQL injection

 Blind SQL injection is a type of SQL injection attack where an attacker can exploit a vulnerability in a web application's input validation to inject malicious SQL statements into the backend database. This attack is called "blind" because the attacker does not receive any feedback or error messages from the application that reveal the results of the injected SQL query.

Where is this attack used?

Blind SQL injection attacks are commonly used in web applications that require user input to access data stored in a backend database. This includes applications such as online shopping websites, social media platforms, and online banking portals.

Why use this attack?

An attacker can use blind SQL injection to gain unauthorized access to sensitive information such as user credentials, financial information, and personal data. They can also use it to modify or delete data in the backend database, which can cause serious damage to the application and its users.

Method of attacks:

Blind SQL injection attacks typically involve injecting SQL code into a vulnerable input field of a web application, such as a search box or login form. The injected code can then execute SQL commands that allow the attacker to access, modify or delete data in the backend database.

To perform a successful blind SQL injection attack, the attacker must identify vulnerable input fields in the web application and use techniques such as Boolean-based or time-based queries to extract information from the database.

How to secure from this attack?

To secure against blind SQL injection attacks, developers should use proper input validation and sanitization techniques when processing user input. They should also use parameterized queries or stored procedures to prevent SQL injection attacks.

Types of Blind SQL injection attacks:

1. Boolean-based: This attack involves injecting SQL code that returns a true or false value depending on the success of the injected SQL statement. The attacker can use this to infer information about the database by asking yes or no questions and analyzing the application's response.

2. Time-based: This attack involves injecting SQL code that causes the application to delay its response, revealing information about the database based on the time it takes to receive a response.

3. Out-of-band: This attack involves using a separate channel, such as email or DNS, to extract data from the database. The attacker can inject SQL code that triggers an action on the application, which then sends a request to a server they control, revealing information about the database.

Here is an example of a blind SQL injection attack:

Suppose a web application has a search field that allows users to search for products by name. The application uses the following SQL query to retrieve results from the backend database:

SELECT * FROM products WHERE name = '{user_input}'

An attacker can inject the following code into the search field to perform a Boolean-based blind SQL injection attack:

' or 1=1--

The resulting SQL query would be:

SELECT * FROM products WHERE name = '' or 1=1--

The double dash "--" is used to comment out the rest of the SQL code, preventing any errors in the SQL syntax. The "or 1=1" part of the injected code always returns true, effectively bypassing the login authentication and granting access to the application.

In conclusion, blind SQL injection attacks are a serious threat to web applications, and developers should take measures to secure their applications against them. Regular security audits and penetration testing can help identify and mitigate vulnerabilities that could be exploited by attackers.