What is the immediate effect of a successful SQL injection attack?

A successful SQL injection attack primarily allows an attacker to gain unauthorized access to data stored in a database. By manipulating SQL queries through input fields, an attacker can retrieve, modify, or delete sensitive information without legitimate authorization. This often includes personal data, credentials, or any other information that the database holds.

The nature of SQL injection exploits the trust that the application places in user inputs, effectively allowing the attacker to execute arbitrary SQL commands. This can lead to serious consequences such as data breaches, data loss, and other security vulnerabilities.

While it might be tempting to consider other options, they do not reflect the critical outcome of an SQL injection attack. For example, increased network speed, improved software performance, and creation of backup files don't result from the exploit; rather, they could lead to degraded performance or data integrity issues in the aftermath of such attacks. Thus, the correct identification of unauthorized data access underscores the primary risk associated with SQL injection vulnerabilities.