PC security fundamentals: If you suspect a computer virus infection, which of the following components is generally <em>not</em> altered or directly infected by typical PC viruses?

Introduction / Context:
Viruses and malware typically target storage and executable code: boot sectors, master boot records, operating system files, and user programs. Understanding common targets helps you prioritize scans and backups when an infection is suspected.

Given Data / Assumptions:

• Classic PC environment with removable media and bootable disks.
• Viruses may infect boot sectors, executable files, and spread via floppies.
• CMOS is a small non-volatile memory that stores system configuration.

Concept / Approach:

Traditional viruses write to the boot sector or infect program files to gain control during startup or execution. They can also copy themselves to removable media like floppy disks. Direct modification of CMOS configuration values by viruses is uncommon; while some malware can change CMOS settings, this is not a typical or necessary infection vector because CMOS stores settings, not executable code.

Step-by-Step Solution:

Verification / Alternative check:

Antivirus logs typically report infected files and boot records, not CMOS edits. BIOS setup changes might occur due to user error or battery issues rather than viral action.

Why Other Options Are Wrong:

• Boot sector: historically a very common malware target.
• Program files: classic file-infecting viruses modify executables.
• Floppy disks: frequently used for propagation in legacy systems.
• None of the above: incorrect because CMOS is the least likely target.

Common Pitfalls:

Confusing malware side effects (like altered boot order) with direct CMOS infection; ignoring bootable media scans; neglecting offline backups before cleaning.

Final Answer:

CMOS