What characterizes polymorphic viruses?

• A. They mutate frequently to escape detection by anti-virus software
• B. They always delete files
• C. They only affect smartphones
• D. They are immune to any antivirus software

Answer: (A)

Polymorphic viruses are defined by their ability to mutate their code with each infection so the same malicious payload ends up looking different every time. They usually accomplish this by encrypting the payload with a new key and using a decryptor that changes form, which lets the virus carry out its action while evading static signature detection. Because the code changes, simple pattern matching used by traditional antivirus software often misses them unless detection relies on behavior, heuristics, or emulation. This mutating behavior is the hallmark, not actions like deleting files, device targets like smartphones, or immunity to antivirus—those aren't inherent to polymorphic viruses.