How to Detect Malware on a Windows PC
A scan is the fastest test, but a few manual checks catch things a scan may rate as merely unwanted.
Automated detection
Run a threat scan with an up-to-date database, then a Microsoft Defender Offline scan if symptoms persist. Two engines disagreeing is informative in itself.
Manual checks
- Startup entries in Task Manager and in Task Scheduler
- Processes with high network usage while the PC is idle
- Recently installed programs in Settings → Apps, sorted by install date
- Browser extensions and their permissions
- Unexpected scheduled tasks running from user-writable folders
Judging what you find
An executable in AppData with a random name and no publisher is a strong signal. A signed vendor updater in Program Files is not. When unsure, search the exact filename plus its full path before deleting anything.
Frequently asked questions
Is high CPU usage always malware?
No. Windows indexing, updates and antivirus scans all cause it. Sustained high usage at idle with no visible cause is the version worth investigating.
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