Programs are also considered malware if they secretly act against the interests of the computer user.

A wide variety of malware types exist, including computer viruses, worms, Trojan horses, ransomware, spyware, adware, rogue software, wiper and scareware. By contrast, software that causes unintentional harm due to some deficiency is typically described as a software bug. Malware (a portmanteau for malicious software) is any software intentionally designed to cause damage to a computer, server, client, or computer network. Hex dump of the Blaster worm, showing a message left for Microsoft co-founder Bill Gates by the worm's programmer