The old image of a virus displaying skull-and-crossbones and announcing itself is outdated. Modern malware tries hard to stay hidden — but it always leaves traces.
1. Unexplained Slowness
If your computer has become slow without any obvious reason — no new software, no Windows update — something may be consuming CPU or memory in the background. Open Task Manager and look for processes using high CPU that you don't recognise.
2. Browser Redirects and New Toolbars
If your searches suddenly go through a different search engine, your homepage has changed, or a toolbar appeared that you didn't install — you have adware or a browser hijacker. This type is annoying but usually not catastrophic.
3. Unexpected Pop-Up Ads
Pop-ups appearing outside your browser — on the desktop itself — are a clear sign of adware. Legitimate software doesn't do this.
4. Antivirus Has Been Disabled
Check that Windows Defender (or your installed antivirus) is still active. Many viruses target antivirus software first because a disabled scanner can't catch them. If you didn't turn it off and it's off, that's a serious red flag.
5. Ransom Note Screens
If files have been renamed with strange extensions and a README is demanding payment, you have ransomware. Stop using the computer, disconnect from the internet and call for professional help immediately — every minute it runs, more files are encrypted.
6. Unknown Programs in the Programs List
Check Settings → Apps. Look for anything installed recently that you don't recognise. Be suspicious of generic names like "PC Optimizer", "Browser Helper" or any software from publishers you've never heard of.
7. High Network Activity When Idle
If your internet light is blinking constantly while you're not doing anything, something may be transmitting data. Open Task Manager → Performance → Open Resource Monitor → Network tab to see what's communicating.
8. Friends Receiving Emails From You That You Didn't Send
Some malware hijacks your email account to spread itself. If people tell you they're getting strange emails from your address, your email is compromised — change your password immediately from a different device.
9. Accounts Locked Out
Multiple failed login attempts you didn't make can trigger account lockouts. If this happens to your Microsoft, Google or bank accounts, your credentials may have been stolen.
10. Your Computer Is Mining Cryptocurrency
Cryptomining malware uses your CPU and GPU to mine coins for criminals. Signs: extreme slowness, very loud fans, computer hot to touch, high electricity bills. Check CPU usage in Task Manager — it should be below 5% when idle.
What to Do
Run Malwarebytes Free immediately. For serious infections — especially ransomware or banking trojans — professional removal is safer than DIY, as some malware persists through standard removal attempts.