Which tool is used to automate SQL injections and exploit a database by forcing a given web application to connect to another database controlled by a hacker?

DataThief automates SQL injection exploitation and includes functionality to force a vulnerable web application's back-end database to initiate outbound connections to a database server under the attacker's control. This out-of-band exfiltration technique allows data extraction even when direct query results are not visible. It is specifically designed for the injection-and-extraction workflow described in the question.

NetCat is a general-purpose network utility for creating TCP/UDP connections and is not designed to automate SQL injection or database exploitation.

Cain and Abel is a Windows-based password recovery and sniffing tool, not a SQL injection automation framework.

SQLInjector is not a recognized, widely documented SQL injection automation tool comparable to DataThief in the context of this question.