Which type of virus is programmed to rewrite itself completely each time it infects a new executable file?

• A. Metamorphic viruses
• B. File extension viruses
• C. Zombie
• D. FAT virus

Answer: (A)

Mutating its entire body to appear different on every infection is a hallmark of metamorphic viruses. These threats rewrite their entire codebase each time they infect a new executable, producing a semantically identical payload but with a completely different sequence of instructions, structure, and even added or altered opcodes. The goal is to defeat signature-based detection by ensuring no two infections look the same, while preserving the malware’s behavior.

This differs from other concepts in the options. Simply changing a file’s extension doesn’t alter the virus’s code or behavior and is just a trick for disguise. A zombie is a compromised device controlled by an attacker and doesn’t describe self-rewriting malware. A FAT virus targets the FAT file system structures, not the self-modifying nature of the code.