What type of attack involves intercepting and altering communications between two parties without their knowledge?

The type of attack that involves intercepting and altering communications between two parties without their knowledge is known as a man-in-the-middle attack. In this scenario, the attacker secretly relays and possibly alters the communication between the two involved parties, making them believe they are directly communicating with each other.

Man-in-the-middle attacks can occur in various forms, such as intercepting unencrypted data over a public Wi-Fi network or using malicious software to gain control over a communication session. The attacker is effectively "in the middle," allowing them to capture sensitive information, manipulate messages, or even impersonate one of the parties involved. This makes it a serious security threat, as it compromises the confidentiality and integrity of the communication.

In contrast, other types of attacks like phishing primarily focus on tricking individuals into revealing sensitive information by impersonating a trusted entity, while brute force attacks involve repeatedly guessing passwords until the correct one is found. SQL injection is a different kind of attack aimed at databases, where attackers execute malicious SQL statements to manipulate database systems. Each of these alternatives targets different vulnerabilities, so the focus on interception and alteration in communications specifically identifies the characteristics of a man-in-the-middle attack.