What type of application self-replicates and degrades system performance without affecting files?

The correct answer is that the application is a Worm. A worm is a type of malicious software that can self-replicate and spread across networks without the need for a host file, unlike viruses, which attach themselves to executable files. Worms primarily exploit vulnerabilities in operating systems and other software to propagate. As they replicate, they consume network bandwidth and resources, which can lead to significant degradation of system performance.

In contrast, viruses tend to affect files by attaching themselves to them and are activated when the infected file is executed. Trojans often disguise themselves as legitimate software but do not self-replicate; instead, they perform harmful actions when executed. Backdoors create unauthorized access points but do not self-replicate like worms do. Understanding these distinctions helps to identify specific threats and the appropriate responses to mitigate their effects on systems.