10 Most Common Types of Computer Viruses (and Malware)

🧟 Trojan Horse (Trojan)

• Disguises itself as a legitimate program.
• Often used to steal data or give hackers access.
• Example: A fake antivirus that actually installs malware.

🧬 Worms

• Self-replicating; spread through networks (like email, USBs).
• Can crash systems or slow down networks.
• Example: WannaCry ransomware worm.

📎 Macro Viruses

• Infect documents (like Word or Excel) using macros.
• Spread via email attachments or shared files.
• Example: Melissa virus.

💣 File Infector Viruses

• Attach to .exe or .com files.
• Spread when the file is opened.
• Example: Virut.

💿 Boot Sector Viruses

• Infects the start-up files of your system.
• Spread via infected USB drives or CDs.
• Example: Michelangelo.

🧠 Resident Viruses

• Hide in your RAM and act in the background.
• Activate when a system function or program runs.
• Example: Randex.

🕵️ Polymorphic Viruses

• Change their code every time they spread.
• Harder for antivirus software to detect.
• Example: Storm Worm.

🌐 Web Scripting Viruses

• Run inside your web browser.
• Triggered by visiting infected websites.
• Example: Samy (Myspace worm).

🧨 Ransomware

• Encrypts files and demands payment to unlock them.
• Spreads via email, infected websites, or software.
• Example: CryptoLocker, WannaCry.

📷 Adware and Spyware (not always viruses but very common)