Which type of malware disguises itself as legitimate software?

The type of malware that disguises itself as legitimate software is known as a Trojan horse. This term originates from the ancient Greek story of the Trojan War, where the Greeks used deception to infiltrate the city of Troy. In the context of cybersecurity, a Trojan horse masquerades as a useful program or file, leading users to unknowingly download and install malicious software that can compromise their systems or steal sensitive data.

Trojan horses do not replicate themselves like viruses or worms; instead, they rely on tricking users into executing them. Once activated, they can perform harmful actions such as stealing personal information, creating backdoors for further attacks, or downloading additional malware. The key characteristic of a Trojan is its ability to appear harmless, making it crucial for users to only download software from trusted sources.

While other types of malware like adware, spyware, and ransomware can present threats, they function differently. For instance, adware is designed to display unwanted advertisements, spyware secretly collects user information, and ransomware encrypts files and demands payment. None of these categories inherently involve the same level of disguise as seen with Trojan horses.