Ethical Hacking Essentials Practice Test

Identify the type of virus that overwrites a part of the host file with null constant while maintaining file size during infection.

1. Cavity Virus

2. Macro Virus

3. Boot sector Virus

4. Logic bomb Virus

The correct answer is: Cavity Virus

The type of virus described is known as a cavity virus. This specific category of virus does not increase the size of the infected file, as it cleverly overwrites sections of the host file with null values. By doing this, it can insert its code without altering the overall file size, making it less detectable by some antivirus programs that might scan for unexpected file size changes. Cavity viruses exploit the unused spaces in a file's structure, effectively embedding their malicious payload while maintaining the original file's integrity and size. This technique provides a layer of stealth, as the functionality of the host file remains intact for users, even while the virus is operational. The other types of viruses mentioned do not exhibit this characteristic. For example, macro viruses typically attach themselves to documents and use macros (automatic commands in software applications) to infect other files, but they do not specifically target unused spaces in files in the same way that cavity viruses do. A boot sector virus infects the disk's boot sector, leading to different behaviors and impacts when a system starts. Lastly, a logic bomb is more about executing malicious code based on specific conditions rather than altering the file structure like a cavity virus does.