Malware, short for malicious software, is designed to disrupt, damage, or gain unauthorized access to computer systems and networks. Among the most common types are viruses, worms, and trojans, each with distinct behaviors and attack mechanisms.
1. Virus
A computer virus is a malicious program that attaches itself to legitimate files or programs and spreads when the infected file is executed.
Key Characteristics:
- Requires user interaction to spread (e.g., opening an infected file).
- Can modify or corrupt files and programs.
- Often spreads through email attachments, removable media, or downloaded files.
Examples of Viruses:
- ILOVEYOU Virus (2000)
- Melissa Virus (1999)
Prevention Measures:
- Regular antivirus scans.
- Avoid opening unknown email attachments.
- Keep software and operating systems updated.
2. Worm
A worm is a self-replicating malware that spreads across networks without human intervention.
Key Characteristics:
- Does not require host files to spread.
- Exploits network vulnerabilities and security flaws.
- Can cause network congestion, data loss, and system slowdowns.
Examples of Worms:
- Blaster Worm (2003)
- Conficker Worm (2008)
Prevention Measures:
- Patch software vulnerabilities.
- Use firewalls and intrusion detection systems (IDS).
- Implement network segmentation.
3. Trojan Horse (Trojan)
A trojan is malware disguised as a legitimate program to trick users into installing it.
Key Characteristics:
- Often delivered through phishing emails or malicious downloads.
- Creates backdoors for unauthorized access.
- Can steal sensitive data, log keystrokes, or deliver additional malware payloads.
Examples of Trojans:
- Zeus Trojan (2007)
- Emotet Trojan (2014)
Prevention Measures:
- Avoid downloading from untrusted sources.
- Use endpoint protection solutions.
- Monitor for unusual system activity.
Comparison Table
| Type | Propagation Method | Requires User Interaction | Primary Target |
|---|---|---|---|
| Virus | File-based infection | Yes | Files and Programs |
| Worm | Network-based | No | Networks and Systems |
| Trojan | Social engineering | Yes | Sensitive Data and System Access |