A rootkit is a collection of tools (programs) that enable administrator-level access to a computer.

A rootkit is a collection of tools (programs) that enable administrator-level access to a computer. This program hides itself deep into an operating system for malicious activity and is extremely difficult to detect. The malicious software operates in a stealth fashion by hiding its files, processes and registry keys and may be used to create a hidden directory or folder designed to keep out of view from a user's operating system and security software.

What privilege level does a rootkit require to infect successfully on a Victim's machine?