Which virus forms a shell around the target host program's code, making itself the original program with the host code as its sub-routine?

Which virus forms a shell around the target host program's code, making itself the original program with the host code as its sub-routine?

• A. File extension viruses
• B. FAT virus
• C. Logic bomb
• D. Shell virus

Answer: (D)

Wrapping the host program with its own code is what a shell virus does. A shell virus places its code around the target program so the host’s executable runs as a sub-routine under the virus’s control. When the infected program starts, the virus code executes first (the “shell”), then transfers control to the original host code, making the virus appear as the original program to the user. This wrapping conceals the true payload by retaining the host’s behavior while hiding the infection inside the wrapper. The other options describe different malware behaviors: changing file extensions or masquerading files, manipulating the FAT to spread, or triggering actions only under certain conditions. They don’t involve wrapping the host program so that the host runs as a sub-routine within a shell.

Wrapping the host program with its own code is what a shell virus does. A shell virus places its code around the target program so the host’s executable runs as a sub-routine under the virus’s control. When the infected program starts, the virus code executes first (the “shell”), then transfers control to the original host code, making the virus appear as the original program to the user. This wrapping conceals the true payload by retaining the host’s behavior while hiding the infection inside the wrapper.

The other options describe different malware behaviors: changing file extensions or masquerading files, manipulating the FAT to spread, or triggering actions only under certain conditions. They don’t involve wrapping the host program so that the host runs as a sub-routine within a shell.