Malware, Threats and Attacks
Cyber security protects computers, networks and data from attack. The three goals are the CIA triad: Confidentiality, Integrity, Availability.
Malware (malicious software)
| Malware | Behaviour |
|---|---|
| Virus | Attaches itself to a host file and spreads when the file is run or shared. Needs user action. |
| Worm | Self-replicates across networks on its own, with no host file. Slows the network. |
| Trojan horse | Looks like a useful program but hides harmful code. Does not replicate. |
| Ransomware | Locks or encrypts files and demands payment. WannaCry (2017) is the famous case. |
| Spyware | Secretly collects information about the user. |
| Keylogger | Records every key pressed to steal passwords. |
| Adware | Shows unwanted advertisements. |
| Rootkit | Hides deep in the system to give an attacker hidden control. |
| Botnet | A network of infected computers ("zombies") controlled remotely. |
| Logic bomb | Harmful code that fires on a condition (a date, an event). |
| Backdoor | A hidden entry that bypasses normal login. |
Attacks and crimes
| Attack | Meaning |
|---|---|
| Phishing | Fake emails or sites to steal passwords or card details. Spear phishing targets one person. |
| Vishing / Smishing | Phishing by voice call / by SMS. |
| Pharming | Redirects you to a fake site even when you type the right address. |
| DoS / DDoS | Floods a server with requests to make it unavailable. DDoS uses many computers. |
| Man-in-the-Middle | Attacker secretly sits between two parties and reads or alters data. |
| Brute force | Tries every possible password. |
| SQL injection | Inserts malicious SQL through an input box to reach the database. |
| Social engineering | Tricks people, not machines, into giving secrets. |
| Spoofing | Pretending to be a trusted source (email, IP or caller ID). |
| Sniffing | Capturing data packets on a network. |
| Zero-day | Attack on a flaw the vendor does not yet know about. |
| Identity theft | Using someone's personal data to cheat. |
| Skimming | Copying card data with a hidden device on an ATM or shop machine. |
| SIM swap | Fraudster gets a duplicate SIM to receive your OTPs. |
| Cyberstalking, cyberbullying | Online harassment. |
Types of hackers
White hat (ethical, with permission), black hat (criminal), grey hat (in between). Ethical hacking and penetration testing are legal security checks.
Keep practising
Notes are only half the work. Test yourself with questions and discuss doubts with other aspirants.
Prepared for exam revision from standard computer textbooks, Microsoft documentation and official sources. Features differ between Excel and Word versions (2016, 2019, 2021, 365) so check which version your exam follows. Found a mistake? Tell us.