Form 1 ICT / Form 2 ICT

Threats to Computer and Data Security

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Recall that Software is a set of instructions that can be executed by a computer system. System software is used to maintain hardware resources, while application software solves end user problems.

There are, however, other categories of software which are meant to be malicious and disruptive to the computer system.

Cartoon of a laptop whose screen shows a shark fin in the water, hinting at hidden danger
Malware (malicious software) can be hiding on a computer, just out of sight
EFF-Graphics, CC BY 3.0 US, via Wikimedia Commons (Malware.png)

Homework

Research and make brief notes on the following terms:

Viruses, malware, spam, antivirus, firewall, worms, Trojan horses, spyware, ransomware, adware.

Homework Solution

Short notes to learn. Each term has a simple definition and the key thing to remember.

Virus

A virus is a harmful program that attaches itself to a normal file or program and copies itself when that file is opened.

Remember: It attaches to a file or program and needs a person to run it before it can spread.
Green computer code on a black screen with the word VIRUS highlighted in red
A virus hides inside normal-looking files and code
Santeri Viinamäki, CC BY-SA 4.0, via Wikimedia Commons (Computer virus illustration.jpg)

Malware

Malware (short for malicious software) is any software made to harm a computer, its data or its user.

Remember: Malware is the umbrella term – viruses, worms, Trojans, spyware, ransomware and adware are all types of malware.

Spam

Spam is unwanted junk messages, usually emails, sent to huge numbers of people at once.

Remember: Spam is unwanted bulk messages – don’t open its links or attachments; some spam is phishing that tries to steal your details.
Illustration of a hand reaching out of an email on a laptop screen to grab a credit card and money
Spam and phishing emails try to trick you into giving away personal or financial information
Mohamed Hassan, CC0, via Wikimedia Commons (Scam-phishing-fraud-email-attack….jpg)

Antivirus

Antivirus software scans your computer for malware, blocks it and removes it.

Remember: It scans for, blocks and removes malware – keep it updated so it knows about the newest threats.
Antivirus program window with Quick Scan, Scan Now and Update Malware Database buttons
An antivirus program: run a scan and keep its malware database up to date
ThomasLiquet, CC BY-SA 4.0, via Wikimedia Commons (Screen Shot of ClamXav Main Screen.png)

Firewall

A firewall is a security system that checks the network traffic going in and out of a computer or network and blocks anything not allowed.

Remember: It filters traffic in and out using rules, like a security guard at the gate.
Diagram of a brick wall labelled Firewall standing between computers on a LAN and computers on a WAN
A firewall sits between your network (LAN) and the outside world (WAN), blocking unwanted traffic
Bruno Pedrozo, CC BY-SA 3.0, via Wikimedia Commons (Firewall.png)

Worm

A worm is a harmful program that copies itself and spreads from computer to computer across a network on its own.

Remember: It spreads by itself across a network – no host file and no user action needed.
A floppy disk in a clear museum display case under a sign reading The Morris Internet Worm source code
This floppy disk holds the Morris Worm (1988), one of the first worms to spread by itself across the Internet
Go Card USA from Boston, USA, CC BY-SA 2.0, via Wikimedia Commons (Morris Worm.jpg)

Trojan horse

A Trojan horse is harmful software that pretends to be a useful or fun program so that you will install it.

Remember: It pretends to be useful or harmless software, but hides something bad inside.
A large wooden sculpture of the Trojan horse on wheels under a blue sky
A Trojan horse is named after the wooden horse from the Greek story – it looks harmless but hides something inside
Stefan Kühn, CC BY-SA 3.0, via Wikimedia Commons (Trojan Horse in Stuttgart 2001.jpg)

Spyware

Spyware is software that secretly watches what you do on your device and sends your information to someone else.

Remember: It secretly watches you and sends your information (like passwords) to someone else.
A magnifying glass held over the keys of a white computer keyboard
Spyware secretly watches what you do – some kinds (keyloggers) even record every key you type
Macedo_Media, CC0, via Wikimedia Commons (SpywareWhiteKeyboard.jpg)

Ransomware

Ransomware is malware that locks or scrambles (encrypts) your files so you cannot open them, then demands payment to unlock them.

Remember: It locks/encrypts your files and demands payment – keeping backups helps you recover.
Cartoon of a computer monitor with a large gold padlock on the screen
Ransomware locks up your files and demands money to unlock them
Lunarbunny, CC BY-SA 3.0, via Wikimedia Commons (Monitor padlock.svg)

Adware

Adware is software that fills your screen with unwanted adverts, such as pop-ups.

Remember: It shows unwanted ads – often installed alongside free downloads.
A fake pop-up advert with a red STOP sign, the words Your PC is infected!, a Scan now button and a link saying Update your antivirus (free)
A fake pop-up advert – never click ads like this; they can lead to adware or worse
Syced, CC0, via Wikimedia Commons (Malvertising.svg)

Summary

TermKey thing to remember
VirusAttaches to a file; needs a person to run it
MalwareUmbrella term for any harmful software
SpamUnwanted bulk messages/email
AntivirusScans for, blocks and removes malware – keep it updated
FirewallFilters traffic in and out using rules (security guard)
WormSpreads by itself across a network
Trojan horsePretends to be useful or harmless
SpywareSecretly watches you and sends your information
RansomwareLocks/encrypts files and demands payment
AdwareShows unwanted ads

Attributions

UPDATES TO THIS POST

2023-09-05 – changed homework components from (Computer viruses, malware, spam, anti- virus, firewall) to (Viruses, malware, spam, antivirus, firewall, worms, Trojan horses, spyware, ransomware, adware.)

October 2026 – Added images and a homework solution.

© 2020 Vedesh Kungebeharry. All rights reserved.

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