sql注入

Galaxy Glossary

How can malicious users exploit SQL queries to gain unauthorized access to data?

SQL injection is a code injection technique used to attack data-driven applications. Attackers insert malicious SQL code into input fields to manipulate database queries and gain unauthorized access to sensitive data.

Thank you! Your submission has been received!

Oops! Something went wrong while submitting the form.

Description

SQL injection is a serious vulnerability that can compromise the security of any application that interacts with a database. It occurs when user-supplied data is not properly sanitized before being used in a SQL query. This allows attackers to inject their own SQL commands into the query, effectively tricking the application into executing unintended actions. For example, an attacker might enter a malicious string into a login form, causing the database to return all user accounts instead of just the one matching the provided credentials. This can lead to data breaches, unauthorized access, and even complete system compromise. Understanding how SQL injection works is crucial for building secure applications. A well-designed application will always validate and sanitize user input to prevent this type of attack.

Why sql注入 is important

SQL injection is a critical security concern because it allows attackers to bypass security measures and gain unauthorized access to sensitive data. Preventing SQL injection is essential for maintaining data integrity and protecting user information.

Example Usage

```sql -- Vulnerable code (DO NOT USE) -- Assume this is part of a login form DECLARE @username VARCHAR(50) = 'user''; DELETE FROM users; --'; DECLARE @password VARCHAR(50) = 'pass'; SELECT * FROM users WHERE username = @username AND password = @password; ``` ```sql -- Corrected code (using parameterized queries) -- This is a much safer approach DECLARE @username VARCHAR(50) = 'user'; DECLARE @password VARCHAR(50) = 'pass'; -- Using parameterized queries DECLARE @sql NVARCHAR(MAX) = N'SELECT * FROM users WHERE username = @username AND password = @password'; DECLARE @cmd NVARCHAR(MAX) = N'EXEC sp_executesql @sql, N'@username VARCHAR(50), @password VARCHAR(50)', @username, @password'; EXEC sp_executesql @cmd; ```

Common Mistakes

Not validating user input before using it in SQL queries.
Using string concatenation to build SQL queries.
Not using parameterized queries.
Not understanding the difference between user input and database commands.

Want to learn about other SQL terms?