Know and understand viruses and malware including how to take preventative action to avoid the danger of infecting a computer from a downloaded file

Published by Patrick Mutisya · 14 days ago

ICT 0417 – Safety and Security: Viruses and Malware

Topic 8: Safety and Security

Objective

Know and understand viruses and malware, including how to take preventative action to avoid the danger of infecting a computer from a downloaded file.

What is Malware?

Malware is any software designed to damage, disrupt, or gain unauthorised access to a computer system.

Common Types of Malware

TypeHow it worksTypical Symptoms
Computer \cdot irusAttaches itself to legitimate programs and spreads when the host program is executed.Slow performance, unexpected pop‑ups, files disappearing.
WormSelf‑replicates across networks without needing a host file.Network congestion, rapid consumption of bandwidth.
Trojan HorseDisguises itself as useful software to trick users into installing it.Unauthorised remote access, data theft.
SpywareCollects information about the user’s activities and sends it to a third party.Unusual ads, changes to browser settings.
AdwareDisplays unwanted advertisements, often bundled with free software.Pop‑up ads, browser redirects.
RansomwareEncrypts files and demands payment for the decryption key.Files become inaccessible, ransom note appears.

How Malware Can Enter Through a Downloaded File

  1. Finding a file on an untrusted website or peer‑to‑peer network.

  2. Downloading the file without verifying its source or integrity.

  3. Opening or executing the file, which may contain hidden malicious code.

  4. Malware installs itself, often silently, and begins its payload.

Preventative Actions

  • Use reputable antivirus/anti‑malware software and keep it updated.

  • Keep the operating system and all applications patched. Security updates close known vulnerabilities.

  • Verify the source of a download. Prefer official websites or trusted vendors.

  • Check file extensions. Beware of double extensions such as document.pdf.exe.

  • Scan downloaded files before opening. Right‑click → Scan with antivirus.

  • Enable a firewall. It blocks unauthorised inbound and outbound traffic.

  • Use strong, unique passwords and two‑factor authentication.

  • Back up important data regularly. Allows recovery if ransomware strikes.

  • Educate yourself on phishing techniques. Do not click links or open attachments from unknown senders.

Step‑by‑Step Checklist for Safe Downloading

  1. Identify the need for the file – is it essential?

  2. Locate the file on a trusted website; look for HTTPS and a reputable domain.

  3. Read user reviews or comments about the file, if available.

  4. Download the file to a designated “Downloads” folder.

  5. Before opening, right‑click the file and select “Scan with [antivirus]”.

  6. If the scan is clean, open the file; otherwise, delete it immediately.

  7. After use, consider moving the file to a secure location or deleting it.

Suggested Diagram

Suggested diagram: Flowchart showing the stages of a malware infection from a downloaded file – from source verification, download, scanning, to execution or safe deletion.

Key Take‑aways

  • Malware includes viruses, worms, trojans, spyware, adware, and ransomware.

  • Downloaded files are a common infection vector; always verify and scan.

  • Regular updates, reliable security software, firewalls, and good backup practices dramatically reduce risk.

  • Awareness and cautious behaviour are the first line of defence.