How to Scan for Malware on Windows 11: A Complete Guide

If your Windows 11 computer has been running slower than usual, throwing strange pop-ups, or behaving oddly, there’s a good chance malware might be the culprit. The thought of malicious software lurking in your system can be scary, but the good news is that Windows 11 comes with strong built-in protection tools—and you can also use third-party programs for extra security.

In this article, I’ll walk you through how to scan for malware on Windows 11 step by step. Whether you’re a casual user or a tech enthusiast, this guide will give you everything you need to keep your PC safe.

Table of Contents

What Is Malware?

Malware is short for “malicious software.” It includes viruses, worms, Trojans, spyware, ransomware, and adware. Basically, anything designed to harm your system, steal your data, or slow down performance falls under malware.

Think of it like unwanted guests who sneak into your house, mess things up, and sometimes even steal your belongings.

How Do You Know If Your PC Has Malware?

Sometimes malware hides silently, but there are common warning signs:

Sluggish performance or frequent crashes
Strange pop-up ads or new programs you didn’t install
Unusual spikes in internet usage
Settings being changed without your consent
Antivirus alerts

If you notice any of these, it’s time for a scan.

Step 1: Use Windows Security (Built-In Antivirus)

The easiest way to scan for malware in Windows 11 is through Windows Security (formerly Windows Defender). It’s free, reliable, and already installed.

Press Windows + I to open Settings.
Go to Privacy & security > Windows Security.
Click Virus & threat protection.
Hit Quick scan.

This runs a fast check on your most vulnerable files and folders.

Step 2: Run a Full Scan

If you want to dig deeper:

In Virus & threat protection, click Scan options.
Choose Full scan.
Click Scan now.

This checks every file on your computer, but it may take over an hour depending on how much data you have.

Step 3: Try a Microsoft Defender Offline Scan

Some malware is sneaky and hides while Windows is running. That’s where the offline scan comes in handy.

Go to Virus & threat protection > Scan options.
Select Microsoft Defender Offline scan.
Restart your PC when prompted.

Your system will reboot, and Defender will run a deep scan before Windows loads.

Step 4: Use Third-Party Antivirus Software

While Windows Security is solid, some users prefer additional layers of protection. Trusted antivirus tools include:

Malwarebytes
Bitdefender
Kaspersky
Norton
Avast

👉 Download only from official websites to avoid fake versions.

Step 5: Run a Custom Scan on Specific Folders

Maybe you downloaded something suspicious, and you want to check only that file or folder.

Right-click the folder.
Select Show more options > Scan with Microsoft Defender.
Wait for the scan results.

This is great for checking USB drives or new downloads.

Step 6: Use Windows PowerShell for a Malware Scan

For advanced users, Windows PowerShell can also trigger scans.

Search for PowerShell, right-click, and choose Run as administrator.
Enter this command:

For a full scan, use:

Step 7: Boot into Safe Mode and Scan

Some malware hides so well that normal scans can’t catch it. Scanning in Safe Mode increases the chances of removal.

Press Windows + R, type msconfig, and hit Enter.
Under Boot, select Safe boot.
Restart your PC.
Run Windows Security full scan.

Afterward, return to msconfig and uncheck Safe boot.

Step 8: Use Windows Malicious Software Removal Tool (MSRT)

Microsoft also provides a monthly tool called MSRT that removes specific widespread threats.

Download from the official Microsoft site.
Run the tool.
Follow on-screen instructions for a quick or full scan.

Step 9: Scan with an Online Antivirus Tool

If you suspect something your installed antivirus missed, try an online scanner. Examples:

ESET Online Scanner
Trend Micro HouseCall
F-Secure Online Scanner

These work without permanent installation and can catch tricky threats.

Step 10: Keep Windows and Apps Updated

Many malware attacks exploit outdated software. Always:

Turn on Windows Update.
Keep browsers and apps updated.
Uninstall unused or suspicious apps.

Step 11: Enable Real-Time Protection

Make sure real-time protection is on, so malware gets blocked immediately instead of waiting for a manual scan.

Open Windows Security.
Go to Virus & threat protection settings.
Ensure Real-time protection is toggled on.

Step 12: Clear Temporary Files Before Scanning

Clearing temp files reduces scan time and sometimes deletes malware hiding there.

Press Windows + R, type temp, and delete everything.
Repeat with %temp%.

Now, rerun your antivirus scan for better results.

Step 13: Use Task Manager to Spot Suspicious Processes

Sometimes malware runs as a hidden process.

Press Ctrl + Shift + Esc to open Task Manager.
Look for strange processes using lots of CPU or memory.
Right-click > Open file location.
If suspicious, scan that file with Defender.

Step 14: Prevent Future Infections

Scanning is good, but prevention is better.

Don’t download files from shady sites.
Avoid pirated software and cracks.
Double-check email attachments before opening.
Use a strong firewall.
Regularly back up important files.

Step 15: When to Seek Professional Help

If malware keeps coming back or if ransomware has locked your files, it’s best to call in a professional or use a dedicated malware removal service.