Malware Basics

Recognize common types

Malware is unwanted software that harms confidentiality, integrity, or availability. Names describe behavior, not a single product.

• Virus / worm — spreads by infecting files or hopping across networks
• Trojan — pretends to be useful software while hiding harmful behavior
• Ransomware — blocks access to files or systems and demands payment
• Spyware / stealers — collect passwords, browsing data, or other secrets
• Adware / PUPs — push unwanted ads or install extra low-quality software

Reduce how it arrives

Install software only from official stores or vendor sites you typed yourself. Keep browsers and operating systems updated. Treat unexpected downloads and “fix your PC” pop-ups as hostile until proven otherwise.

Respond without panicking

Disconnect from Wi-Fi or Ethernet if the machine is actively misbehaving, note what you saw, and use built-in security tools or a trusted scanner from a known-good source. Avoid downloading random “cleaner” tools from search ads.

When to get help

If banking or work data may be exposed, contact the bank or IT help desk promptly. Paying a ransom does not guarantee recovery and can fund further crime; restore from clean backups when possible.