During which phase does a virus replicate and spread?

The propagation phase is when a virus actively replicates and spreads to other systems or files. This is a crucial part of a virus's lifecycle because it allows the malicious code to disseminate and infect additional hosts, significantly increasing its impact. During this phase, the virus uses various methods to ensure its copies are distributed, such as attaching itself to legitimate files, exploiting network vulnerabilities, or leveraging user actions like opening infected files.

In contrast, the dormant phase refers to the period after a virus has been introduced to a system but before it becomes active; it does not replicate or spread during this time. The triggering phase involves the activation of the virus after certain conditions are met, such as a specific date or action by the user. The execution phase is where the virus carries out its payload, which could involve damaging data or disrupting system functions, but again, it does not primarily focus on replication. Hence, the propagation phase is the definitive stage for the replication and spread of a virus.