Which of the following is the least threat for virus infection?

Correct option is A

Among the choices, an online (network) printer is the least likely vector for typical end-user virus infections. Malware commonly spreads via portable storage devices (autorun, infected executables), freeware downloads from untrusted sites (bundled malware/PUPs), and email attachments (macro/scripted payloads, phishing). Printers can have vulnerabilities, but exploiting them usually targets the device itself (e.g., DoS, data leakage), not infecting a user’s PC with commodity viruses. By contrast, user-initiated actions—opening attachments, running installers, or plugging USBs—directly execute code on the host, posing higher risk. Hence, (a) represents the least threat for virus infection to the user’s computer.
Important Key Points
1. Typical infection paths: USB drives, malicious installers, and booby-trapped attachments execute code on the host.
2. Printer risk profile: Network printers may expose config/data or be used for lateral movement, but they rarely install malware on PCs without additional exploits.
3. User behavior factor: Social engineering (phishing, fake updates) greatly increases risk from downloads and emails.
4. Mitigations: Disable autorun, use real-time AV/EDR, keep OS/applications patched, and restrict macros/scripts.
5. Email hygiene: Verify sender, scan attachments, prefer viewer modes, and block executable attachments at the gateway.
6. Download safety: Use trusted vendors/stores; validate hashes/signatures where possible; avoid “cracked” or repacked freeware.
Knowledge Booster
· (b) Portable storage devices: High risk—USBs can carry worms; autorun.inf and infected binaries can trigger on plug-in.
· (c) Downloaded free software: Risky—often bundles adware or trojans; supply-chain or “cracked” builds are common infection sources.
· (d) Downloaded email attachment: Very common vector—malicious Office macros, PDFs with exploits, or disguised executables.
· Even with printers, ensure firmware is current, change default creds and segment them on the network to limit broader security impact.