What is the primary purpose of a rootkit?

The primary purpose of a rootkit is to allow control of a system remotely. Rootkits achieve this by modifying the operating system and can conceal their presence, thereby allowing unauthorized users to gain elevated privileges and perform various malicious activities without detection. They can create backdoors and enable attackers to manipulate system functionalities, access sensitive information, and execute commands as if they were unauthorized administrators.

In the context of rootkits, control over the system is a fundamental aspect because it allows the attacker to maintain persistent access and perform actions that can further compromise the system, such as data theft, surveillance, or using the system as part of a botnet. This capability goes beyond simple functionalities like displaying ads, encrypting files, or replicating itself—these actions can be components of broader attacks, but they do not encapsulate the primary function of rootkits, which centers around maintaining control over the compromised system.