How can you avoid security risks when writing SQL queries?

1 Use parameterized queries

One of the easiest and most effective ways to prevent SQL injection attacks is to use parameterized queries, also known as prepared statements or bind variables. Parameterized queries separate the SQL code from the user input, so that the input is treated as a literal value rather than as part of the SQL statement. This way, malicious input cannot alter the logic or structure of the query. Most programming languages and frameworks support parameterized queries, and you should always use them when dealing with user input or dynamic values.

2 Validate and sanitize input

Another important measure to avoid security risks when writing SQL queries is to validate and sanitize the input before passing it to the query. Validation means checking that the input meets certain criteria, such as data type, length, format, or range. Sanitization means removing or escaping any potentially harmful characters, such as quotes, semicolons, or comments, that could interfere with the SQL syntax. You can use built-in functions or libraries to perform validation and sanitization, or implement your own logic. However, you should not rely on validation and sanitization alone, as they may not catch all possible cases of malicious input.

3 Limit permissions and privileges

Another way to avoid security risks when writing SQL queries is to limit the permissions and privileges of the users or applications that execute the queries. This means granting only the minimum level of access that is necessary for the functionality of the query, and revoking any unnecessary or unused permissions. For example, you can use the principle of least privilege (POLP) to assign roles and permissions to users or applications based on their needs and responsibilities. You can also use views, stored procedures, or functions to restrict the access to certain tables, columns, or operations.

4 Encrypt and hash sensitive data

Another technique to avoid security risks when writing SQL queries is to encrypt and hash sensitive data, such as passwords, credit card numbers, or personal information. Encryption means transforming the data into a different form that can only be read by authorized parties who have the key. Hashing means generating a fixed-length string from the data that cannot be reversed. Both encryption and hashing can protect the data from being exposed or stolen if the database is compromised. You can use built-in functions or libraries to perform encryption and hashing, or use external tools or services.

5 Test and review your queries

The last but not least tip to avoid security risks when writing SQL queries is to test and review your queries before deploying them to production. Testing means verifying that your queries work as intended and do not cause any errors or performance issues. You can use tools or frameworks to perform automated or manual testing, or use a staging or development environment to simulate the production conditions. Reviewing means examining your queries for any potential vulnerabilities or flaws that could be exploited by attackers. You can use tools or frameworks to perform code analysis, or use peer review or code audit to get feedback and suggestions.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?