Which type of attack aims to disrupt the normal functioning of a targeted server, service, or network?

The type of attack that aims to disrupt the normal functioning of a targeted server, service, or network is known as a Distributed Denial of Service (DDoS) attack. This form of attack typically involves overwhelming a target with an enormous volume of traffic or requests, rendering the server or service unable to respond to legitimate users.

In a DDoS attack, multiple compromised systems (often part of a botnet) are used to flood the target with traffic from various sources. This makes it extremely challenging to mitigate the attack since it’s difficult to block traffic from numerous different IP addresses without affecting legitimate users. The primary goal of a DDoS attack is not to breach security but to disrupt services and degrade performance, highlighting its distinctiveness from other types of attacks.

The other options represent different attack vectors: a man-in-the-middle attack refers to intercepting and altering communications between two parties; phishing attacks aim to deceive individuals into disclosing sensitive information, such as usernames and passwords; and SQL injection involves manipulating an application's query language to gain unauthorized access to a database. While each of these poses significant risks to security, their objectives differ fundamentally from the disruption focus of a DDoS attack.