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SQL Injection.md

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What is SQL Injection?

SQL Injection (SQLi) is a common type of cyber attack that targets databases through web applications. It allows attackers to manipulate SQL queries executed by the application's database, potentially gaining unauthorized access to sensitive information or even control over the database.

How Does SQL Injection Work?

  • Input Fields: Web applications often use input fields (like login forms, search bars, or user inputs) where users can enter data.

  • Malicious Input: Attackers input specially crafted SQL commands into these fields instead of regular data.

  • Execution: When the application fails to properly validate or sanitize the input, it directly incorporates the attacker's input into SQL queries without proper safeguards.

  • Database Interaction: The attacker's malicious SQL commands are executed by the database server, allowing them to perform unauthorized actions such as retrieving, modifying, or deleting data.

Example Scenario:

Consider a simple login form on a website. The application takes a username and password from the user and checks them against a database to authenticate.

  • Legitimate Input: A user enters their username and password as usual.
  • Malicious Input: An attacker enters a specially crafted input like ' OR '1'='1. This input manipulates the SQL query to always return true, effectively bypassing the login authentication.

Impact of SQL Injection:

  • Data Leakage: Attackers can extract sensitive information from databases, including user credentials, personal data, or financial records.

  • Data Manipulation: SQL Injection can allow attackers to modify or delete data within the database, potentially causing data loss or damage.

  • Unauthorized Access: Attackers may gain unauthorized access to administrative features or privileged accounts within the application.

Mitigating SQL Injection:

  • Parameterized Queries: Use parameterized queries or prepared statements to separate SQL code from user input, preventing direct concatenation of input into SQL queries.

  • Input Validation and Sanitization: Validate and sanitize user input to remove or encode potentially harmful characters before incorporating them into SQL queries.

  • Least Privilege Principle: Restrict database permissions for application accounts to minimize the impact of successful SQL Injection attacks.

  • Web Application Firewalls (WAF): Implement WAFs to detect and block malicious SQL Injection attempts at the network level.

Conclusion:

SQL Injection is a significant threat to web applications that interact with databases. By understanding how SQL Injection works and implementing appropriate mitigation measures such as parameterized queries and input validation, developers can significantly reduce the risk of exploitation and safeguard sensitive data. Regular security testing and updates are essential to maintaining a secure software environment.