The hallmark of a Worm is its ability to self-replicate and spread autonomously across networks, which aligns with the symptoms described: high network utilization and automatic propagation. While both Viruses and Worms can spread and cause harm, Viruses require some form of user action (like executing a file) to replicate, which is not suggested by the scenario. Bots typically perform automated tasks and may participate in large networks (botnets), but the specifics described (high network utilization, identical packets, no user interaction) align more closely with the behavior of a Worm. Logic bombs execute malicious actions when triggered by specific events, but do not self-replicate or spread across networks autonomously.