Windows 10 Fall Creators Update Controlled Folder Access Nullifies Ransomware Attacks
One of the things Microsoft included in the recently released Fall Creators Update is a feature called "Controlled folder access." When enabled, this feature prevents unauthorized access to important files by locking down folders and only allowing authorized apps to access the contents. Unauthorized apps, including malicious executable files, DLLs, and scrips are stopped dead in their tracks.
"Encryption should protect your data and files. Ransomware twists the power of encryption against you and uses it to take files hostage... Controlled folder access brings you right back in control of determining what programs can access your data. This feature protects your files from tampering, in real-time, by locking folders so that ransomware and other unauthorized apps can’t access them. It’s like putting your crown jewels in a safe whose key only you hold," Microsoft says.
For this feature to work, you need to have the Fall Creators Update installed (for Windows Insiders, it is included in every release dating back to Insider Preview build 16232). Controlled folder access also requires that Windows Defender's real-time protection is enabled.
Controlled folder access automatically protects common folders where documents and other important are stored on your primary storage device, but you have the option of configuring it to protect additional folders, including ones that reside on other drives. You can also mark apps as trusted, which can come in handy when using unique or custom programs.

To enable (and/or customize) Controlled folder access, open up the Windows Defender Security Center. Click on the shield icon labeled Virus & threat protection, then click on Virus & threat protection settings. Scroll down to Controlled folder access and flip the switch to On. You will then see clickable options for Protected folder and Allow an app through Controlled folder access where you can customize the settings.
When we enabled the feature, it blocked Photoshop CC from saving the above image. Our hunch is that we will run into this on occasion at the outset, but the time spent configuring the feature is a small price to pay for added protection against ransomware.