100 Days of SQL


Day 45 – SQL Injection

SQL injection is a type of security vulnerability that occurs when an attacker is able to inject malicious SQL code into an application’s database query, either through user input or by other means. This can allow the attacker to access or modify data in the database, or even execute arbitrary code on the server hosting the database.

The vulnerability typically arises when an application fails to properly validate user input or sanitize it before using it in a SQL query. For example, if an application accepts user input for a search query and constructs a SQL query based on that input without validating or sanitizing it, an attacker could insert their own SQL code as part of the input and execute it in the context of the query.

Some common techniques used by attackers to exploit SQL injection vulnerabilities include:

  • Commenting out parts of the original SQL query and adding their own code
  • Using UNION statements to combine the results of different queries
  • Using subqueries to retrieve or modify data in the database
  • Using time delays to obfuscate the attack and avoid detection

To prevent SQL injection vulnerabilities, it is important to use secure coding practices, such as:

  • Using parameterized queries, prepared statements, or stored procedures to sanitize user input
  • Validating input data to ensure it matches the expected format and does not contain unexpected characters or values
  • Limiting the privileges of the database user used by the application to only the necessary operations and data access
  • Regularly updating and patching the database software and application code to fix known vulnerabilities

In summary, SQL injection is a serious security vulnerability that can have significant consequences if exploited. It is important for developers to be aware of this vulnerability and take steps to prevent it in their applications.