Windows Security includes several scan types, and each one has a purpose. Quick scan is best for routine checks, Full scan is for deeper suspicion, and Microsoft Defender Offline scan is for stubborn threats that may hide while Windows is running.
Does this affect you?
Use this for Windows 10 and Windows 11 PCs using the built-in Windows Security app, also known as Microsoft Defender.
Run a Quick scan or Full scan
Start with Quick scan for normal checks, then use Full scan when something still feels wrong.
- Open Start, type Windows Security, and open the app.
- Choose Virus & threat protection.
- Click Quick scan for a fast check of common malware hiding places.
- For a deeper scan, choose Scan options, select Full scan, and click Scan now.
- Let a Full scan finish completely, even if it takes an hour or more.
- If threats are found, choose Start actions and Remove or Quarantine each item.
- Restart the PC afterward so cleanup actions can finish.
Run Microsoft Defender Offline scan
Use this when threats keep returning or you suspect something hiding from normal scans.
- Open Windows Security > Virus & threat protection > Scan options.
- Select Microsoft Defender Offline scan.
- Click Scan now.
- Save open work because the PC will restart automatically.
- Let the offline scan run in its minimal environment.
- After Windows restarts, review results under Protection history.
Get a second opinion
No scanner catches everything.
- Download Malwarebytes Free from malwarebytes.com.
- Install and open it.
- Click Scan and wait for it to complete.
- Quarantine or remove anything it finds.
- Restart if prompted.
More control
Quick scan vs. Full scan
Quick scan checks the places malware most often hides and also runs automatically. Full scan checks the whole drive and is worth using when symptoms remain or an earlier scan found trouble.
Keep real-time protection on
Windows Security scans periodically when real-time protection is enabled. Check Virus & threat protection settings and keep Real-time protection on.
A clean scan is a snapshot
No threats found means nothing matching known malware or suspicious behavior appeared during that scan. Keep protection and updates enabled afterward.
Escalate if symptoms remain
If unknown programs, disabled security settings, or strange network activity continue after Quick scan, use Full scan or Offline scan.
Sources
- Microsoft Support – Stay protected with Windows Security (2025)
- Microsoft Support – Run a Microsoft Defender Offline scan (2025)
- Malwarebytes – How to remove malware from a Windows PC (2025)