Malware is software intentionally created or modified to perform unauthorized or harmful actions on a computer, device, or network. The term covers distinct families and functions, including viruses, worms, trojans, spyware, botnet clients, and ransomware; a single sample may combine several capabilities. Its behavior—not its label—determines the security concern: it may execute code, persist, alter or encrypt data, steal credentials, or provide unauthorized remote access.
For practitioners, malware reporting is most useful when it identifies the family or tool conservatively and provides evidence such as affected platforms, samples, infrastructure, or observed behavior. Defenses include promptly patching vulnerable software, restricting execution and privileges, monitoring endpoints and networks, maintaining tested backups, and isolating suspected systems for analysis. Detection should use behavior and verified indicators rather than names alone, since variants change. If malware processes personal or regulated data, investigations should also address privacy, evidence preservation, and applicable reporting obligations.