Sql injection Attack

Introduction:

SQL injection is a type of security exploit that allows attackers to manipulate the SQL statements executed by a web application.It is one of the most common and dangerous vulnerabilities in web applications. In this document, we will cover the basics of SQL injection, how it works, and how to prevent it.

What is SQL Injection?

SQL injection is a technique used to attack web applications that use SQL databases. The goal of SQL injection is to trick the application into executing SQL statements that the attacker has crafted. This can be done by inserting SQL code into user input fields, such as a login form, search form, or any other input field that allows user input to be used in SQL statements.

The impact of a successful SQL injection attack

A successful SQL injection attack can result in unauthorized access to sensitive data, such as passwords, credit card details, or personal user information. Many high-profile data breaches in recent years have been the result of SQL injection attacks, leading to reputational damage and regulatory fines. In some cases, an attacker can obtain a persistent backdoor into an organization's systems, leading to a long-term compromise that can go unnoticed for an extended period.

Some common SQL injection examples:

• Retrieving hidden data, where you can modify a SQL query to return additional results.
• Subverting application logic, where you can change a query to interfere with the application's logic.
• UNION attacks, where you can retrieve data from different database tables.
• Examining the database, where you can extract information about the version and structure of the database.
• Blind SQL injection, where the results of a query you control are not returned in the application's responses.

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Example of SQL Injection:

Consider a login page that accepts a username and password. The SQL statement that is executed to check if the user is valid may look like this:

SELECT * FROM users WHERE username = 'username' AND password = 'password'

An attacker can enter a specially crafted username and password that will modify the original SQL statement to look like this:

SELECT * FROM users WHERE username = '' OR 1=1 --' AND password = '' OR 1=1 --

The SQL injection attack added the following code to the original SQL statement:

' OR 1=1 --

This code tells the SQL server to ignore the password field and return all records where the username is empty or where 1 equals 1 (which is always true). The double dash "--" is used to comment out the rest of the original SQL statement.

Note: Take care when injecting the condition OR 1=1 into a SQL query. Although this may be harmless in the initial context you're injecting into, it's common for applications to use data from a single request in multiple different queries. If your condition reaches an UPDATE or DELETE statement, for example, this can result in an accidental loss of data.

This attack will return all records in the users table, effectively bypassing the login mechanism and giving the attacker access to the application.

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How to Prevent SQL Injection?

To prevent SQL injection, developers need to properly validate and sanitize all user input. Here are some best practices for preventing SQL injection:

Use prepared statements with parameterized queries or use an ORM to sanitize input and prevent malicious SQL statements from being executed.

Use parameterized queries: Parameterized queries use placeholders for user input and are executed separately from the SQL statement. This ensures that user input cannot modify the original SQL statement.

Sanitize all user input: All user input should be sanitized to remove any potential SQL code. This can be done by stripping out any special characters or by using a library or framework that handles input sanitization.

Use the least privilege: Use database users with the least amount of privilege necessary to perform their tasks. This reduces the risk of a successful SQL injection attack.

Keep your software up-to-date: Security vulnerabilities are often discovered and patched in newer versions of software. Keep your software up-to-date

to ensure that you are using the latest security patches.

**References: SQL injection cheat sheet SQL injection cheat sheet of invicti

https://github.com/KathanP19/HowToHunt/blob/master/SQLi/SQL_Injection.md https://owasp.org/www-project-web-security-testing-guide/latest/4-Web_Application_Security_Testing/07-Input_Validation_Testing/05-Testing_for_SQL_Injection https://book.hacktricks.xyz/pentesting-web/sql-injection