What Are the Capabilities of mysql_real_escape_string() That Exceed Those of addslashes()?

In web development, functions like mysql_real_escape_string() and addslashes() play crucial roles in safeguarding applications from SQL injection attacks. However, understanding the nuances between these functions is essential to ensure optimal security.

The Role of DB-Specific Functions

While there may be alternative options like parameterized queries, database-specific functions like mysql_real_escape_string() offer specific advantages:

• Tailored for Specific Databases: These functions are tailored to handle the unique characteristics of a particular database system, such as MySQL.

Capabilities of mysql_real_escape_string()

mysql_real_escape_string() enhances addslashes() by adding slashes to additional characters, including:

• \x00
• \n
• \r
• \
• '
• "
• \x1a

In contrast, addslashes() only adds slashes to the following characters:

• '
• \
• NUL

Vulnerability to SQL Injection with addslashes()

Despite its functionality, a webapp that relies solely on addslashes() remains vulnerable to SQL injection attacks. This is because addslashes() does not escape all characters that could potentially be exploited, particularly double-quotes (").

For instance, consider the following query:

SELECT * FROM users WHERE username = '" . addslashes($_POST['username']) . "';

An attacker could bypass the addslashes() protection by inputting a username like " OR 1 = 1. This would result in the following query:

SELECT * FROM users WHERE username = "" OR 1 = 1";

This query would return all users in the database, as the condition " OR 1 = 1" always evaluates to true, allowing the attacker access to sensitive data.

Conclusion

While addslashes() offers basic protection against SQL injection, mysql_real_escape_string() provides a more robust defense by escaping a wider range of characters specific to MySQL. As such, for maximum security, web developers should prioritize using database-specific functions like mysql_real_escape_string() or consider adopting parameterized queries to eliminate any vulnerabilities associated with input handling.