When it comes to your personal computer, few things are more insidious than malware. Fortunately, every PC running Windows 10 has at least one application trying to protect it from the pain and suffering of a malware infection. It is called Windows Defender.
But sometimes, malware can outsmart Windows Defender by hiding within Windows while the operating system is running. To remove the more clever and devious malware, like rootkits, out in the wild you may have to run Windows Defender in offline mode. It is fairly easy to do, but not many people know it is an option because it is buried deep in the settings.
Here's how to turn on Windows Defender Offline and have it scan your PC outside the Windows 10 operating system.
Do it offline
Type settings in the Cortana search box or say "settings" if she is listening and click the Settings app, which should be the first search result. You should be looking at the screen shown in Figure A.
Click the Update & Security app and then click the Windows Defender item in the navigation window. Scroll down the page until you reach the Windows Defender Offline section, shown in Figure B.
Click or tap the Scan Offline button to start the process. Be forewarned: There is no Are You Sure? dialog after you click that button. Your PC will automatically restart, so save all your work and close any other open applications.
Windows 10 will indeed restart, but not straight into the operating system. Instead Windows Defender will scan your system for malware. The scan will likely take anywhere from just a few minutes to somewhere around 15 minutes—it just depends on your system. If any malware is found, you will be asked if you want to remove it, which you probably should.
Windows 7 and 8
In the past, for versions of Windows prior to Windows 10, you would have to create a bootable USB flash drive, CD-ROM, or DVD to run Windows Defender Offline, but the Microsoft support website doesn't include the download for that application anymore. Apparently, Windows 7 and 8 can now run Windows Defender Offline the same way we do in Windows 10. Could someone confirm this for us? Share your advice and experiences in the discussion below.
Mark W. Kaelin has been writing and editing stories about the IT industry, gadgets, finance, accounting, and tech-life for more than 25 years. Most recently, he has been a regular contributor to BreakingModern.com, aNewDomain.net, and TechRepublic.