Which type of virus disguises itself by using a similar file name and a different file extension?

The Companion virus is characterized by its ability to disguise itself by utilizing a similar file name to a legitimate program, while employing a different file extension. This technique is employed to trick users into executing the virus, believing they are opening a trusted file. For instance, a Companion virus might create a file named "document.txt" alongside a legitimate "document.doc" file. When a user opens the "document.doc," if the Companion virus is running, it can execute simultaneously, often unbeknownst to the user.

Other types of malware function differently. A Trojan virus may appear as a legitimate program but typically does not use a specific mechanism involving file name and extension manipulation. Worms are designed to replicate themselves and spread through networks or systems without needing to attach to another file. Ransomware encrypts data on a user's system and demands payment for its release, rather than using file naming tricks to hide its presence. Understanding how Companion viruses operate highlights the need for vigilance when downloading or executing files with similar names or differing extensions.