SQL injection is a type of code injection attack that allows an attacker to execute malicious SQL code on a web application's database. This can be done by inserting malicious code into a web form or other input field that is used to interact with the database.
Once the malicious code is executed, the attacker can gain access to sensitive data, modify or delete data, or even take control of the database server. SQL injection attacks are one of the most common web application security vulnerabilities, and they can have a devastating impact on organizations.
Here are some examples of SQL injection attacks:
Retrieving hidden data: An attacker can modify a SQL query to return additional results that are not normally visible to users. For example, an attacker could modify a query that is used to retrieve a user's account information to also return the user's password.
Subverting application logic: An attacker can change a SQL query to interfere with the application's logic. For example, an attacker could modify a query that is used to update a user's account information to instead delete the user's account.
UNION attacks: An attacker can use UNION attacks to retrieve data from different database tables. This can be used to gain access to sensitive data that is not normally visible to users.
There are a number of steps that can be taken to mitigate the risk of SQL injection attacks, including:
Filtering user input: Web applications should filter all user input before it is used to interact with the database. This can be done by using a regular expression to match and remove malicious code.
Using prepared statements: Prepared statements are a way of executing SQL queries that can help to prevent SQL injection attacks. When a prepared statement is used, the SQL query is first parsed and compiled by the database server. This means that the attacker cannot inject malicious code into the query at runtime.
Keeping software up to date: Software updates often include security fixes for known vulnerabilities. It is important to keep all software up to date, including web applications and database servers.
By following these steps, you can help to protect your web applications from SQL injection attacks.