IIST-SI-000228 - Non-ASCII characters in URLs must be prohibited by any IIS 10.0 website.
Setting limits on web requests ensures availability of web services and mitigates the risk of buffer overflow type attacks. The allow high-bit characters Request Filter enables rejection of requests containing non-ASCII characters.
Follow the procedures below for each site hosted on the IIS 10.0 web server: Open the IIS 10.0 Manager. Click the site name under review. Double-click the 'Request Filtering' icon. Click 'Edit Feature Settings' in the 'Actions' pane. Uncheck the 'Allow high-bit characters' check box.