“Virus” is the word most people use, but today’s threats are broader: adware, spyware, ransomware, cryptominers and fake “cleaner” apps. Together they’re called malware. Here’s how to recognize it, remove it and keep it out.
Warning signs of malware
- Pop-up ads appearing even when your browser is closed.
- Your browser’s homepage or search engine changed on its own.
- New toolbars, extensions or programs you didn’t install.
- The computer suddenly runs slow or the fans run constantly.
- Security software has been turned off and won’t turn back on.
- Friends receive strange messages or emails from your accounts.
- Files are encrypted or renamed and there’s a ransom note. That’s ransomware.
None of these alone proves an infection, but several together are a strong signal.
How malware gets in
- Fake downloads: “free” versions of paid software, cracked games, or fake download buttons.
- Email attachments and links: especially invoices, shipping notices or “urgent” documents.
- Fake update pop-ups: “Your Flash/browser/driver is out of date, click here.”
- Bundled software: extra programs hidden in installers.
- Unpatched software: security holes in old operating systems and apps.
What to do if you think you're infected
1. Disconnect from the internet
This stops malware from sending your data out or spreading. If you suspect ransomware, do this immediately.
2. Run a full scan
- Windows: Open Windows Security → Virus & threat protection → Scan options. Run a Full scan, then a Microsoft Defender Offline scan, which restarts your PC and catches malware that hides while Windows is running.
- Second opinion: A free on-demand scanner like Malwarebytes can catch adware and unwanted programs that others miss.
- Mac: macOS has built-in protection, but a reputable scanner like Malwarebytes for Mac is useful for adware.
3. Remove suspicious programs and extensions
Uninstall programs you don’t recognize (Settings → Apps → Installed apps on Windows, or the Applications folder on Mac). Remove unknown browser extensions.
4. Change your passwords, from a clean device
If malware was present, assume passwords may have been captured. Change your most important ones first (email, banking), using a different, trusted device, and turn on two-factor authentication.
5. Consider a reset
For serious infections, especially ransomware or anything that keeps coming back, a full reset or reinstall of the operating system is the most reliable fix. That’s why backups matter.
If you're hit by ransomware
Don’t rush to pay. Disconnect the device, check whether your backups are intact, and report it to Report Fraud. Free decryption tools exist for some ransomware strains at nomoreransom.org.
How to stay protected
- Keep your operating system, browser and apps updated automatically.
- Keep built-in protection (Windows Security or macOS protections) turned on.
- Only download software from official sources.
- Be suspicious of unexpected attachments and “urgent” pop-ups.
- Use a standard (non-admin) account for everyday use if you can.
- Keep backups, including one that isn’t permanently connected to your computer.
The bottom line
Modern built-in security is good, but it can’t protect you from everything you click. Stay updated, stay sceptical, and keep backups. Then even a worst-case infection is a bad day, not a disaster.
