Which type of malicious software is characterized by its capability to infect and copy itself?

The type of malicious software characterized by its ability to infect and replicate itself is a virus. A virus attaches itself to legitimate programs or files and, when executed, can replicate by inserting copies of itself into other programs or files on the same host system. This replication allows viruses to spread from one computer to another when infected files are shared or executed on different systems.

In contrast, a worm is a type of malware that self-replicates and spreads independently over networks without needing to attach itself to another program. Trojans disguise themselves as legitimate software but do not replicate or spread on their own, as their primary purpose is to deceive users into executing them. A botnet refers to a network of compromised machines that are controlled by an attacker, and while it can be formed by various types of malware, it does not specifically refer to self-replicating malware.