How to scan for and remove malware with Windows Security

Malware is harmful software installed on your device without your knowledge. Viruses, spyware and ransomware are common kinds.

Signs you may have malware

The Federal Trade Commission lists these: the computer slows down, freezes or crashes; the browser's home page changes or sends you to sites you didn't choose; new toolbars or add-ons appear; you get a lot of pop-up ads; you see repeated error messages.

Steps

1. Stop signing in to sensitive accounts. Until the computer is clean, don't use it for banking or shopping.
2. Open Windows Security. Select Start, type Windows Security and open it. Select Virus & threat protection.
3. Check for protection updates. Under Virus & threat protection updates, make sure the security intelligence is current.
4. Run a Quick scan. Select Quick scan. It takes less time than a full scan, and when it is done Windows Security tells you if it recommends one of the other scans.
5. Run a Full scan. Select Scan options, choose Full scan, then Scan now. It scans every file and program on the computer, so it takes much longer.
6. Run the offline scan. In Scan options, choose Microsoft Defender Antivirus (offline scan). Save your work first: the PC restarts and scans before Windows loads, which makes it harder for stubborn malware to hide. To see the results afterwards, open Windows Security and select Protection history.
7. Let Windows Security deal with what it finds. Threats it has stopped are listed under Current threats and in Protection history.
8. Change your passwords afterwards. In case the malware gave someone access to your accounts, change your passwords from the clean computer and turn on two-step verification. Start with your email.

If you use other security software

If another antivirus program is installed, Microsoft Defender Antivirus turns itself off automatically, and the scan buttons are in that program instead. Every Tech Support Bundle plan includes Webroot antivirus; the idea is the same: update it, then run a scan.

If that didn't work

If a threat keeps coming back, or Windows Security won't open or won't update, stop using the computer for anything private. The FTC's advice is to get help from a company you know and trust.

What not to do

Never call a phone number shown in a pop-up warning, and don't download a “cleaner” from an advertisement. Both are common ways people get malware in the first place.