For an instructor lead, in-depth look at learning SQL click below.
Structured Query Language (SQL) serves as the foundation for manipulating and retrieving data stored in relational databases. However, if not handled carefully, it can expose your application to several security vulnerabilities, with the most notorious one being SQL injection.
What Is SQL Injection?
SQL Injection refers to an attack that occurs when an attacker manipulates SQL queries to interfere with the application’s interaction with its database. This interference can lead to unauthorized data viewing, altering, and in worst cases, deletion.
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-- Normal SQL Query for user login SELECT * FROM users WHERE username = 'Bob' AND password = 'XYZ' |
If an attacker manipulates the query, here’s what could happen:
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-- Injected SQL query SELECT * FROM users WHERE username = '' OR ''='' AND password = '' OR ''='' |
The code segment above will always return true ! This means the attacker gains unauthorized access.
Preventing SQL Injection
1. Use Parameterized Queries or Prepared Statements
These allow developers to define all the SQL code in advance, and then pass each parameter to the query later. This lets your database distinguish between code and data, regardless of what input is supplied.
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-- An example of a parameterized query SELECT * FROM users WHERE username = @user AND password = @pass |
2. Use Stored Procedures
Stored procedures will compile the SQL code once and store the execution plan for later. An added benefit is that parameters supplied to the stored procedure are typed, adding an additional layer of security.
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-- Calling a stored procedure EXEC s<a href="mailto:p_GetUser @Username" >p_GetUser @Username</a> = 'Bob', @Password = 'XYZ' |
3. Regular Updates and Code Review
Routinely updating your database and codebase, combined with periodic code reviews, helps fortify your application against new threats and vulnerabilities.
Conclusion
Investing in understanding SQL injection and applying preventative measures against it is crucial for the security of your application. Always remember the golden rule when it comes to writing secure SQL: never trust user input. Always make sure input data is sanitized and treated as potentially dangerous.
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-- Happy Safe Coding! |