What 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 form of malware tricks users into downloading or executing it by presenting itself as a useful or benign application. Once activated, a Trojan horse can perform harmful actions on the user's system, such as stealing data, creating backdoors for further attacks, or installing additional malicious software. The deceptive nature of Trojans is what makes them particularly dangerous, as users may willingly install them, believing they are legitimate tools or applications.

In contrast, while adware is indeed a type of malware that can be bundled with legitimate software and may lead to unwanted advertisements, it does not inherently disguise itself in the same way a Trojan horse does. A virus typically attaches itself to other files and spreads when those files are shared, while a worm is a standalone malware program that replicates itself to spread across networks. Neither viruses nor worms rely on disguising themselves as legitimate applications to propagate. This distinct characteristic of Trojans as being masqueraders is why they are classified in this manner.