Computer Virus and Cyber Security — Patwari Notes
The basics of computer viruses and cyber security — types of malware (Virus, Worm, Trojan, Ransomware), the role of antivirus and firewalls, and basic online safety habits — explained here at RSCIT level for the Patwari exam.
- RSCIT-level depth
- 7 min read
What is a Computer Virus?
A Computer Virus is a malicious program that enters a computer without the user's knowledge, self-replicates, and can damage files, programs or the entire system. It spreads from one computer to another through an infected file, a USB drive, an email attachment, or an unsafe website.
The word 'virus' is often used generally for all kinds of harmful software (malware), but technically there are several different kinds of malware, each working in a different way.
Types of Malware
| Type | Identification |
|---|---|
| Virus | Makes copies of itself; needs a host file to spread |
| Worm | Similar to a virus, but can spread through a network on its own, without needing a host file |
| Trojan Horse | Installs deceptively by looking like a useful/genuine program |
| Spyware | Spies on the user's activity (such as passwords) |
| Ransomware | Locks/encrypts data and demands a ransom (money) in exchange for releasing it |
| Adware | Repeatedly shows advertisements (ads) without permission |
The main difference between a Trojan Horse and a Virus is that a Trojan does not make copies of itself, but gets in by deception — this difference is asked about in exams.
Antivirus and Firewall
Antivirus software is a program that scans a computer to identify and remove viruses and other malware — for example, Windows Defender (built into Windows), Quick Heal, Norton, McAfee. It is necessary to keep antivirus software updated regularly, because new viruses keep being created every day.
A Firewall is a security system that acts like a wall between a computer and the internet — it decides what data can come into the computer and what can go out, so that unauthorized access can be blocked.
Basic Online Safety Habits
Do not click on attachments or links in unknown emails — this is the most common method of Phishing, in which passwords or bank information are stolen through a fake email/website that looks genuine. Keep a strong password (combining letters, numbers and special characters) and do not share it with anyone. Before entering information on any government or banking website, be sure to check for 'https' and the lock icon in the address bar.
Do not plug an unknown USB drive into a computer without checking it, keep software and antivirus updated regularly, and avoid sensitive activity such as banking or payments on public Wi-Fi.
Memory Trick / Exam Tip
Trick to remember Virus vs Trojan: a Virus 'spreads' on its own (by making copies), a Trojan gets in 'hidden' (disguised as genuine software). And https + the lock icon = the first sign of a trustworthy website.
Frequently Asked Questions
What is a computer virus?+
A computer virus is a harmful program that enters a computer without the user's knowledge, makes copies of itself, and damages files/systems.
What does ransomware do?+
Ransomware locks or encrypts a user's data and demands a ransom (money) in exchange for getting it back.
What is phishing?+
Phishing is a fraud technique in which someone's password or bank information is stolen through a fake email or website that looks genuine.
What does a firewall do?+
A firewall acts like a security wall between a computer and the internet, blocking unauthorized data from entering or leaving the computer.