In this article, we will discuss five important steps to take to ensure the security of your WordPress plugin or theme software.
By following these steps, you can help to protect your WordPress site from common security threats and vulnerabilities.
1. Use prepared statements and parameterized queries
Prepared statements queries can help to prevent SQL injection attacks by separating the code that defines a database query from the data that is used in the query.
This can help to protect your WordPress site’s database from malicious input.
For example
$query = $wpdb->prepare(
"SELECT *
FROM $wpdb->posts
WHERE post_status = %s
AND post_type = %s",
'publish',
'post'
);
$posts = $wpdb->get_results( $query );
In this example, the $wpdb global object is used to interact with the WordPress database.
The prepare() method is used to create a prepared statement, which helps to protect against SQL injection attacks.
The statement includes placeholders (%s) for the values that will be passed when the query is executed.
In this case, the query selects all published posts from the wp_posts table.
The get_results() method is then used to execute the query and return the results as an array of objects.
Prepared queries are especially important when using user-provided information, such as a user name, in a database query.
They prevent malicious users from ‘injecting’ SQL into the query because it will not be accepted as valid.
For information on prepared database statements in WordPress see How to protect your database queries using prepared statements.
2. Use encryption for sensitive data
Sensitive data, such as passwords, should be encrypted to protect it from unauthorized access.
WordPress provides several functions for encrypting data, such as the wp_hash_password() and wp_encrypt() functions.
For example
// Encrypt the string before saving it to the database $encrypted_string = wp_encrypt( $string ); // Save the encrypted string to the database update_option( 'my_option', $encrypted_string ); // Retrieve the encrypted string from the database $encrypted_string = get_option( 'my_option' ); // Unencrypt the string when retrieving it from the database $string = wp_decrypt( $encrypted_string );
In this example, the wp_encrypt() function is used to encrypt the $string variable before it is saved to the database using the update_option() function. When the string is retrieved from the database using the get_option() function, it is unencrypted using the wp_decrypt() function. This allows you to securely save sensitive information to the database without exposing it in plain text.
3. Validate user input
Never trust user input. Use validation to ensure that it is in the correct format and meets your requirements.
Invalid or malicious input can cause errors or security vulnerabilities, so it’s important to validate user input before using it in your WordPress code.
For more information on validating user input in WordPress see How to validate different types of data in WordPress.
4. Avoid exposing sensitive information
Sensitive information, such as database credentials and error messages, should not be exposed to users or external sources.
This information should be kept private and should be accessed only by authorized users and applications.
This can be done by carefully reviewing your website to see that no sensitive information appears to users.
You may also need to disable WP_DEBUG after development to ensure error messages don’t appear and leak information.
5. Use a secure development process
A secure development process can help to ensure that your WordPress code is safe and secure.
This may include things like using version control, conducting code reviews, and performing security testing.
By following a secure development process, you can help to prevent security vulnerabilities and ensure that your WordPress code is of high quality.
An example of a secure development process would look like this:
- Define the plugin’s functional requirements and design a secure architecture.
This should include identifying any sensitive data that the plugin will handle, such as user passwords or financial information, and designing the plugin to handle this data securely. - Implement the plugin’s code using secure coding practices.
This should include using appropriate data types and validation rules to ensure that user input is properly sanitized and validated, avoiding the use of insecure functions or deprecated APIs, and following best practices for authentication and access control. - Test the plugin thoroughly to identify and fix any security vulnerabilities.
This should include testing the plugin’s inputs and outputs using both valid and invalid data, simulating common attack scenarios, and reviewing the plugin’s code for potential vulnerabilities. - Deploy the plugin securely.
This should include using secure hosting and storage solutions, implementing robust access control measures, and monitoring the plugin for potential security issues. - Maintain the plugin regularly to ensure that it remains secure.
This should include regularly applying security updates and patches, monitoring the plugin for potential security issues, and responding quickly to any reported vulnerabilities.