Malware
12 signs your computer has spyware (and how to remove it)
Is your computer infected with spyware? Here are twelve warning signs to look for on Windows and Mac, plus a clear, step-by-step process to find and remove the infection.
21 April 2026 · 8 min read
Computer spyware can lurk for months, quietly harvesting your passwords, browsing and files. Unlike a flashy virus, good spyware wants to stay invisible — but it changes how your machine behaves in detectable ways. Here are twelve signs to watch for, and a clear process to clean an infected computer.
The warning signs
1. Sudden slowness
Spyware consumes processing power and memory to run and transmit data. A computer that has become sluggish without explanation — especially one that was fine recently — may be running something hidden.
2. Constant disk or network activity when idle
If your hard drive light flickers constantly or your network activity is high when you are not doing anything, something is working in the background.
3. The fan runs hard for no reason
Like slowness, persistent fan activity on an idle machine points to hidden processes consuming resources.
4. Browser changes you did not make
A new homepage, an unfamiliar search engine, or toolbars and extensions you never installed are classic signs of adware and browser-hijacking spyware.
5. A flood of pop-ups
Aggressive pop-up ads, especially outside the browser or on sites that should not have them, indicate adware.
6. Redirected searches
If your searches route through an unfamiliar engine or your clicks land on unexpected pages, spyware is intercepting your browsing.
7. New programs you did not install
Unfamiliar applications in your programs list — particularly ones that launch at startup — deserve investigation.
8. Disabled security tools
Spyware often tries to disable antivirus and firewalls to protect itself. If your security software keeps turning off or you cannot enable it, that is a serious red flag.
9. Crashes and instability
Lower-quality spyware destabilises systems, causing freezes, crashes and error messages that were not happening before.
10. Unfamiliar network connections
Tools that show active connections may reveal your computer talking to unknown servers — the spyware sending your data home.
11. Account compromises
If accounts get breached despite strong passwords, a keylogger may be capturing them as you type.
12. The webcam light flickers on its own
An indicator light activating when you are not using the camera can signal spyware accessing it. Treat it seriously.
How to remove computer spyware
- Disconnect from the internet to stop data exfiltration and remote control while you work.
- Review running processes (Task Manager on Windows, Activity Monitor on macOS) and note anything unfamiliar consuming resources.
- Check startup programs and browser extensions, removing entries you do not recognise.
- Uninstall suspicious programs through the system's apps list.
- Scan suspicious files. If you isolate an unknown executable, upload it to the scanner to confirm whether it is malicious.
- Run a full security scan with a reputable tool and let it quarantine what it finds.
- Change your passwords from a different, clean device — the spyware may have captured them.
Preventing reinfection
Once clean, keep your operating system and software updated, install programs only from official sources, avoid pirated software, use a password manager and two-factor authentication, and scan downloads before running them. Most computer spyware enters through a careless download or an unpatched vulnerability — close those, and you close the door. For the broader picture of how infections happen, see our guide on how malware spreads.
Frequently asked questions
How do I know if it is spyware or just a slow computer?
Look for combinations of signs — slowness plus unfamiliar programs plus unexpected network activity is far more telling than any single symptom, which could have ordinary causes.
Can Macs get spyware?
Yes. While historically targeted less than Windows, Macs face real spyware and adware threats. The same detection and removal principles apply.
Will reinstalling the operating system remove spyware?
A clean reinstall removes virtually all software-based spyware. Back up your files first, scan them before restoring, and change your passwords from a clean device afterwards.