What type of attack aims to exploit weaknesses in a system through unauthorized access?

Unauthorized access refers to the act of gaining entrance to a system, network, or data without authorization. This type of attack intentionally targets vulnerabilities in a system, allowing an intruder to bypass security measures and exploit sensitive information or resources. The objective is often to manipulate, steal, or damage data, or to disrupt services.

In the context of this question, the focus is on attacks that seek to exploit weaknesses to gain unauthorized entry, which aligns directly with the concept of unauthorized access. This form of attack highlights the importance of robust security protocols, such as user authentication and access controls, to prevent malicious actors from compromising a system.

Phishing, on the other hand, generally involves deceiving users into providing sensitive information, such as passwords, often through misleading messages or websites. Brute force attacks focus on systematically attempting to guess passwords or encryption keys until the correct one is found. Social engineering encompasses a broader range of manipulative tactics used to trick individuals into revealing confidential information, but it does not directly define the act of unauthorized access itself.

Thus, while all the choices reflect different strategies or tactics associated with systems security and attacks, unauthorized access specifically denotes the act of exploiting system weaknesses to gain unauthorized entry, making it the best answer in this context.