1. Malware
Malware (malicious software) is a broad term used for any software intentionally designed to cause damage, steal data, disrupt operations, or gain unauthorized access to computer systems. Malware can affect computers, servers, mobile devices, and networks.
Key points:
- It includes viruses, worms, trojans, ransomware, spyware, etc.
- Malware can spread through emails, infected websites, downloads, or removable media.
- Its goals may include data theft, spying, financial fraud, or system damage.
2. Virus
A virus is a type of malware that attaches itself to a legitimate program or file. It spreads when the infected file is executed by the user.
Key points:
- Requires human action to spread (e.g., opening a file).
- Can corrupt or delete files.
- Often spreads through email attachments or pirated software.
3. Worm
A worm is a self-replicating malware that spreads automatically across networks without user interaction.
Key points:
- Exploits security vulnerabilities.
- Can spread very quickly.
- Often causes network congestion or system slowdowns.
4. Trojan
A Trojan (Trojan Horse) disguises itself as legitimate or useful software but performs malicious actions once installed.
Key points:
- Does not self-replicate.
- Often used to create backdoors for attackers.
- Commonly spread via fake software, email links, or cracked programs.
5. Ransomware
Ransomware encrypts a victim’s files or locks their system and demands payment (ransom) to restore access.
Key points:
- Often demands payment in cryptocurrency.
- Can cause severe data loss if backups are unavailable.
- Spread through phishing emails, malicious downloads, or exploits.
6. Spyware
Spyware secretly monitors user activity and collects sensitive information without consent.
Key points:
- Gathers data such as passwords, browsing habits, and personal information.
- Often runs silently in the background.
- Used for identity theft or corporate espionage.
7. Adware
Adware displays unwanted advertisements on a user’s device, often redirecting browsers to advertising websites.
Key points:
- May track browsing behavior.
- Often bundled with free software.
- Usually less dangerous but can slow systems and invade privacy.
8. Rootkit
A rootkit is malware designed to gain and hide administrator-level access to a system.
Key points:
- Extremely difficult to detect.
- Can disable security software.
- Allows attackers long-term control over a system.
9. Keylogger
A keylogger records every keystroke typed on a device.
Key points:
- Captures passwords, messages, and credit card details.
- Can be software-based or hardware-based.
- Often used in spying or financial theft.
10. Botnet
A botnet is a network of infected devices (called “bots” or “zombies”) controlled remotely by an attacker.
Key points:
- Used for DDoS attacks, spam distribution, or malware spread.
- Users are often unaware their device is part of a botnet.
- Controlled via command-and-control servers.
Summary Table
| No. | Term | Definition (Short) | Main Purpose | Spreads Automatically |
|---|---|---|---|---|
| 1 | Malware | Any malicious software | Damage, theft, disruption | Depends on type |
| 2 | Virus | Attaches to files/programs | Corrupt data | ❌ No |
| 3 | Worm | Self-replicating malware | Rapid spread | ✅ Yes |
| 4 | Trojan | Disguised malicious software | Backdoor access | ❌ No |
| 5 | Ransomware | Encrypts files for ransom | Extortion | ❌ No |
| 6 | Spyware | Secretly monitors activity | Data theft | ❌ No |
| 7 | Adware | Displays unwanted ads | Advertising profit | ❌ No |
| 8 | Rootkit | Hides attacker access | Stealth control | ❌ No |
| 9 | Keylogger | Records keystrokes | Steal credentials | ❌ No |
| 10 | Botnet | Network of infected devices | Large-scale attacks | ✅ Yes |
