CEH courseware describes rootkits as specialized malware designed to conceal their presence while providing persistent, unauthorized access to system-level functions. Rootkits typically modify low-level components of the operating system-such as kernel modules, drivers, or system processes-to hide files, processes, registry keys, and network connections. Their primary purpose is to grant attackers administrative privileges without triggering alerts, making them extremely stealthy and dangerous. CEH emphasizes that rootkits often accompany other malware to maintain long-term control after initial compromise. In contrast, viruses replicate by attaching to files, keyloggers record keystrokes but do not hide system-level access, and ransomware encrypts data rather than conceals operations. The defining characteristics in this scenario- cloaking activity, providing admin-level control, persisting undetected-are directly aligned with rootkit behavior as described in CEH training material.