Know and understand the operation of removing/quarantining viruses using up to date software

Networks and Virus Management – Cambridge IGCSE ICT 0417 (2026‑2028)

1. Objective

Students will be able to:

• Identify the main components of a computer system and a network.
• Explain how ICT is used in a range of real‑world applications.
• Describe the systems life‑cycle and evaluate each stage.
• Understand the principles of safety, security, privacy and legal use of digital resources.
• Use up‑to‑date antivirus/anti‑malware software to detect, quarantine and remove viruses, and evaluate the effectiveness of different approaches.
• Apply good practice in file management, document production, spreadsheets, databases, presentations and website authoring.

2. Computer System Components

Component	Function	Typical Examples (IGCSE relevance)
Central Processing Unit (CPU)	Executes instructions; the “brain” of the computer.	Intel Core i5, AMD Ryzen 5, ARM Cortex‑A72 (used in tablets).
RAM (Random‑Access Memory)	Temporary storage for data being processed; fast but volatile.	4 GB DDR4 in a school laptop.
ROM / Firmware	Permanent instructions for booting and basic hardware control.	BIOS/UEFI, embedded firmware in a router.
Internal Storage	Long‑term data retention; magnetic or solid‑state.	500 GB HDD, 256 GB SSD.
External Storage	Portable media for backup or transfer.	USB flash drive, external HDD, SD card.
Input Devices	Capture data for the computer.	Keyboard, mouse, touchscreen, scanner, microphone, digital camera.
Output Devices	Present processed data to the user.	Monitor, printer, speakers, projector, VR headset.
Peripheral Interfaces	Connect input/output devices.	USB, HDMI, Bluetooth, Wi‑Fi, Ethernet, NFC.

3. Core Network Hardware & Wireless Technologies

Device	Function in a Network	Typical Use‑Case (Examples)
Network Interface Card (NIC)	Provides a physical (wired) or logical (wireless) link to a network.	Ethernet NIC in a desktop PC; Wi‑Fi NIC in a laptop.
Hub	Repeats incoming signals to all ports; no intelligence.	Small classroom where traffic is minimal.
Switch	Forwards frames only to the destination port using MAC addresses.	Office LAN with multiple workstations and printers.
Router	Connects separate networks (e.g., LAN ↔ Internet) and routes traffic using IP addresses.	Home broadband router providing Wi‑Fi and wired ports.
Wireless Access Point (WAP)	Provides Wi‑Fi coverage for wireless devices.	School computer lab with IEEE 802.11ac coverage.
Bluetooth (IEEE 802.15.1)	Short‑range wireless link for peripherals and low‑volume data.	Connecting a wireless mouse or headset to a laptop.

4. Effects of Using ICT

• Health – Ergonomic posture, 20‑20‑20 rule for eye strain, regular breaks to avoid musculoskeletal problems.
• Environmental – Energy consumption, e‑waste, recycling of electronic devices.
• Social & Ethical – Digital divide, responsible use, impact on relationships and learning.
• Micro‑processor Devices – Smartphones, tablets, IoT sensors; must be kept up‑to‑date to prevent malware.

5. ICT Applications (Real‑World Contexts)

Domain	Typical Application	Key Features
Communication	Email, instant messaging, video‑conferencing.	Netiquette, attachments, encryption.
Modelling & Simulation	Physics simulations, climate models, traffic flow.	Data input, visual output, scenario testing.
Control Systems	Industrial PLCs, home automation, robotics.	Sensor input, real‑time feedback, remote monitoring.
Banking & Finance	Online banking, ATMs, mobile payment apps.	Secure authentication, encryption, transaction logs.
Medical & Healthcare	Electronic health records, tele‑medicine, diagnostic imaging.	Confidentiality, data integrity, interoperability.
Retail & E‑commerce	Online stores, point‑of‑sale systems, inventory management.	Secure payment gateways, stock tracking.
Expert Systems & AI	Chatbots, recommendation engines, diagnostic assistants.	Knowledge bases, rule‑based reasoning, machine learning.
Recognition Technologies	OCR, OMR, RFID, NFC, biometric fingerprint/face scanners.	Data capture, authentication, inventory control.
Satellite & GPS	Navigation apps, weather forecasting, remote sensing.	Geolocation, real‑time data streams.

6. Systems Life‑Cycle (SLC)

The SLC is a structured approach to developing, maintaining and evaluating ICT solutions.

1. Analysis – Identify user needs, constraints, and define requirements.
2. Design – Produce logical (data flow, ER diagrams) and physical (hardware, software) designs.
3. Implementation – Build or configure the system; write code, install hardware.
4. Testing & Evaluation – Verify that the system meets requirements; user acceptance testing.
5. Documentation – Produce user manuals, technical guides, and maintenance records.
6. Maintenance & Review – Update, troubleshoot, and evaluate long‑term performance.

Evaluation (AO3): For each stage, consider alternatives (e.g., cloud vs. local hosting), cost, security, and impact on users.

7. What Is a Computer Virus?

A computer virus is a malicious program that can replicate itself and spread from one device to another, often without the user’s knowledge. Variants include worms, trojans, ransomware, spyware, ad‑ware and rootkits.

7.1 How Viruses Spread in Networks

• File sharing – shared network folders, USB sticks, external drives.
• Email – infected attachments or malicious links.
• Web downloads – compromised sites, fake software installers.
• Network services – SMB, FTP, Remote Desktop Protocol (RDP).
• Unpatched vulnerabilities – OS or application exploits.
• Wireless connections – insecure Wi‑Fi (WPA2‑PSK) or Bluetooth pairing.
• Social engineering – phishing, baiting, pretexting.

8. Functions of Antivirus / Anti‑Malware Software

Function	Description
Real‑time scanning	Monitors files, processes and memory as they are accessed.
Signature‑based detection	Matches code fragments against a database of known virus signatures.
Heuristic / Behaviour analysis	Detects suspicious code patterns or actions (e.g., rapid file encryption).
Cloud‑based lookup	Queries remote threat‑intel servers for the latest definitions, reducing local update frequency.
Quarantine	Moves suspect files to a secure folder where they cannot execute.
Automatic updates	Downloads new virus definitions and software patches on a scheduled basis.
Firewall integration	Blocks unauthorised inbound/outbound connections based on rules.
Web protection	Filters malicious URLs, blocks phishing sites and blocks drive‑by downloads.
Ransomware protection	Monitors for rapid file encryption and creates secure restore points.

9. Step‑by‑Step: Removing or Quarantining a Virus

1. Update the antivirus software. Ensure the latest virus definitions and program patches are installed.
2. Run a full system scan. Include hidden/system files and all removable media.
3. Review the scan report. Identify files marked as infected, suspicious or potentially unwanted.
4. Quarantine the identified files. Move them to the quarantine folder so they cannot run.
5. Decide on repair or deletion.
   • If a clean backup exists, restore the original file.
   • If no backup is available, delete the infected file permanently.
6. Restart in Safe Mode (if required). Some malware only unloads when Windows runs with minimal services.
7. Run a second scan. Verify that no further threats remain.
8. Patch the operating system and all applications. Install the latest security updates.
9. Document the incident. Record:
   • Virus type and symptoms
   • Entry point (e.g., email attachment)
   • Actions taken (quarantine, repair, deletion)
   • Lessons learned and preventive measures
10. Evaluate the response (AO3). Consider:
    • Was the chosen antivirus the most appropriate tool?
    • Could the infection have been prevented by different user behaviour or network controls?
    • What improvements can be made to the backup strategy?

10. Best Practices for Keeping Antivirus Software Up to Date

• Enable automatic definition updates and schedule them outside peak usage hours.
• Set regular full scans (e.g., weekly) and quick daily scans.
• Use a reputable security suite that includes firewall, anti‑phishing and ransomware protection.
• Maintain reliable backups – both offline (external HDD) and cloud‑based (encrypted).
• Educate users about safe browsing, email handling and the dangers of unknown downloads.

11. Network Security, Authentication & Legal Responsibilities

• Password creation – Minimum 8 characters, mix of upper‑ and lower‑case letters, numbers and symbols; avoid common words and reuse.
• Multi‑factor authentication (MFA) – Combine something you know (password) with something you have (token, smartphone app) or something you are (biometrics).
• Authentication devices – Smart cards, USB security tokens, fingerprint readers.
• Encryption – Use WPA3 for Wi‑Fi, TLS/SSL for web traffic, and full‑disk encryption for laptops.
• Data‑protection legislation (GDPR‑style)
  • Personal data must be processed lawfully, fairly and transparently.
  • Collect only what is necessary; store securely; delete when no longer needed.
  • Individuals have the right to access, correct and erase their data.
• Legal responsibilities – Schools and businesses must:
  • Maintain an up‑to‑date privacy policy.
  • Report data breaches to the relevant authority within 72 hours.
  • Ensure staff receive regular e‑safety training.

12. e‑Safety & Threats

• Safe browsing – Verify HTTPS, avoid pop‑up ads, use ad‑blocking extensions.
• Phishing awareness – Look for misspelled domains, unexpected attachments, urgent language.
• Ransomware protection – Keep backups, never pay ransom, isolate infected machines.
• Firewalls – Enable the built‑in OS firewall; configure rules to block unnecessary inbound traffic.
• Malware sandboxing – Run suspicious files in a virtual environment before opening.

13. Audience, Copyright & Legal Use of Digital Resources

• Analysing the audience – Identify purpose, age, knowledge level and accessibility needs before creating any digital artefact.
• Copyright basics
  • Only use material you own, that is in the public domain, or that is licensed for your purpose (e.g., Creative Commons‑BY).
  • Give proper attribution where required.
  • Software must be used under a valid licence; piracy is illegal and punishable.
• Licensing models – Freeware, shareware, open‑source, commercial licences, site licences for schools.
• Consequences of infringement – Legal action, loss of reputation, school disciplinary measures.

14. Communication – Email, Internet Use & Evaluating Information

• Email etiquette – Clear subject, appropriate greeting, concise body, proper sign‑off, use CC/BCC wisely.
• Netiquette – Respectful tone, no shouting (ALL CAPS), avoid excessive emojis in formal contexts.
• Internet protocols
  • HTTP / HTTPS – Transfer web pages; HTTPS adds encryption.
  • FTP / SFTP – File transfer (SFTP adds security).
  • SMTP / POP3 / IMAP – Email sending and retrieval.
  • SSL/TLS – Secure sockets layer for encrypted connections.
• Evaluating sources (AO3)
  • Authority – Who is the author? Are they an expert?
  • Accuracy – Is the information supported by evidence?
  • Currency – When was it published or last updated?
  • Bias – Does the source have a particular agenda?
  • Relevance – Does it answer the question or meet the task?

15. File Management & Data Organisation

• Use a logical folder hierarchy (e.g., Year/Subject/Topic).
• Adopt consistent naming conventions: YYYYMMDD_ProjectName_Version.ext.
• Enable file extensions to be visible; hide system files only when necessary.
• Regularly back up important files – 3‑2‑1 rule (3 copies, 2 media types, 1 off‑site).
• Use version control for collaborative documents (e.g., cloud‑based revision history).

16. Working with Images, Layout & Styles

• Image formats – JPEG (photographs, lossy), PNG (transparent graphics, lossless), GIF (simple animation), SVG (vector).
• Resolution – 72 dpi for web, 300 dpi for print; avoid up‑scaling low‑resolution images.
• Colour models – RGB for screens, CMYK for printing.
• Styles – Use paragraph and character styles for consistent headings, body text and captions.
• Layout tools – Grids, guides, alignment, wrapping, and tables for structured documents.

17. Proofreading & Quality Assurance

• Run spell‑check and grammar tools, then read aloud to catch context errors.
• Use the “track changes” feature for peer review.
• Check accessibility: alt‑text for images, sufficient colour contrast, logical heading order.
• Validate hyperlinks and ensure all references are correctly cited.

18. Graphs & Charts – Selecting & Creating the Right Visual

Data Type	Recommended Visual	Key Features to Include
Comparisons of discrete categories	Bar chart (vertical or horizontal)	Clear axis labels, consistent bar width, data values.
Trends over time	Line graph	Evenly spaced time intervals, markers for key points.
Proportions of a whole	Pie chart (limited to ≤6 slices)	Percentage labels, distinct colours.
Distribution of a data set	Histogram	Appropriate bin size, frequency axis.
Relationships between two variables	Scatter plot	Trend line, axis scales, data point markers.

19. Document Production (Word Processing)

• Use templates for consistency (letterhead, report layout).
• Apply heading styles (H1‑H4) for automatic table of contents generation.
• Insert headers/footers with page numbers, document title, and date.
• Utilise mail‑merge for personalised letters or certificates.
• Export to PDF for fixed formatting and easy sharing.

20. Spreadsheets – Core Features

• Structure – Worksheets, cells, rows, columns, named ranges.
• Formulas & Functions – Basic arithmetic, SUM, AVERAGE, IF, VLOOKUP, COUNTIF, date & time functions.
• Data visualisation – Insert charts, conditional formatting, sparklines.
• Data validation – Restrict entries to lists, numbers or dates.
• Pivot tables – Summarise large data sets quickly.
• Protection – Lock cells, protect worksheets, password‑protect the file.

21. Databases – Fundamentals

• Tables – Rows (records) and columns (fields). Each table should have a primary key.
• Relationships – One‑to‑one, one‑to‑many, many‑to‑many (implemented via foreign keys or junction tables).
• Queries – Use SELECT statements or query‑by‑example to retrieve specific data.
• Forms – User‑friendly data entry screens.
• Reports – Formatted output for printing or sharing.
• Normalization – Reduce redundancy by organising data into related tables (1NF, 2NF, 3NF).

22. Presentations – Slide Design & Delivery

• Use a master slide for consistent fonts, colours and logos.
• Limit text – aim for 6‑word lines and 6‑bullet points per slide.
• Incorporate high‑quality images, charts and short video clips.
• Apply subtle transitions; avoid distracting animations.
• Prepare speaker notes and rehearse timing.

23. Website Authoring – HTML & CSS Basics

• HTML structure – <!DOCTYPE html>, <html>, <head>, <body>.
• Common tags: <h1>–<h6>, <p>, <a href="...">, <img src="..." alt="...">, <ul>/<ol>, <table>.
• CSS basics – selectors, properties (colour, margin, padding), external stylesheet linking.
• Responsive design – use meta viewport and flexible grid layouts.
• Publish via FTP/SFTP or cloud hosting (e.g., GitHub Pages, Google Sites).

24. Impact of Networks on Virus Management

Network Effect	Positive Impact	Negative Impact
Centralised updates	All devices receive the latest antivirus definitions simultaneously.	If the update server is compromised, malware can be propagated to every client.
Shared resources (network drives, printers)	Quarantined files can be stored on a dedicated server for analysis.	Infected files on shared drives can spread rapidly to many users.
Network monitoring & IDS/IPS	Unusual traffic patterns can be detected early, allowing swift isolation.	Encrypted traffic may hide malicious activity from inspection tools.
Remote assistance tools	IT staff can clean infected machines without being on‑site.	If remote tools are hijacked, attackers gain full system control.

25. Health & Micro‑Processor Devices (The Effects of Using IT)

• Ergonomic health – Adjust chair height, keep monitor at eye level, use a wrist rest for keyboards.
• Screen time management – Follow the 20‑20‑20 rule; use blue‑light filters in the evening.
• Micro‑processor‑controlled devices – Smartphones, tablets, wearables, IoT sensors; keep firmware up‑to‑date to prevent botnet recruitment.
• Environmental impact – Recycle old devices, choose energy‑efficient hardware, switch off equipment when not in use.

26. Summary Flowchart – Virus Removal Process