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SQL Injection Types & Prevention


SQL Injection is a type of cyberattack that targets web applications and databases by manipulating SQL (Structured Query Language) queries. It occurs when an attacker inserts or "injects" malicious SQL code into input fields or parameters of a web application, which is then improperly executed by the application's backend database. This can lead to unauthorized access, data theft, data manipulation, or even complete control of the database.

There are different types of SQL Injection attacks:

  • Classic SQL Injection:
- In classic SQL Injection, attackers input malicious SQL code directly into an application's form fields or URL parameters.

- Example: Consider a login form where a user inputs their username and password. An attacker could enter the following as the username:

' OR '1'='1 

The SQL query might become:

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

This query always evaluates to true, allowing the attacker to log in without a valid password.

  • Blind SQL Injection:
- In blind SQL Injection, the attacker doesn't directly see the results of the injected query but can infer information based on the application's behavior.

- Example: An attacker might use a payload like:

' OR 1=1 -- 

The presence or absence of certain application behaviors can indicate whether the condition is true or false.

  • Time-Based Blind SQL Injection:
- Similar to blind SQL Injection, but the attacker introduces time-based delays to determine if the query is true or false.

- Example: An attacker might use a payload that causes a delay, like:

' OR IF(1=1, SLEEP(5), 0) --

If the application experiences a delay, the attacker knows the condition is true.


To prevent SQL Injection attacks, web developers should use parameterized queries or prepared statements, which ensure that user inputs are treated as data rather than executable code. Additionally, input validation and proper escaping of user-generated data are essential security measures. Regularly updating and patching the software, following security best practices, and conducting security testing can help safeguard against SQL Injection vulnerabilities.