Which virus changes the extensions of files?

• A. File extension viruses
• B. Zombie
• C. Win32/Simile
• D. Time bombs

Answer: (A)

Understanding how malware can disguise its payload by changing file extensions is what this item focuses on. A file extension virus intentionally alters the extensions of existing files to hide their true type or to cause the system to treat them differently. For example, it might rename a harmless document like report.doc to report.doc.exe, so the file looks like a document but actually contains an executable. This helps the malware spread and tricks users into opening a malicious program or simply prevents normal file handling.

The other concepts described don’t center on this disguise technique. A zombie refers to a compromised machine that's used as part of a botnet for coordinated actions. Time bombs are malware that activates after a specific date or condition. Win32/Simile is a Windows malware family with various behaviors, not defined by changing file extensions.