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.

Note: If either of the following is true, this requirement is Not Applicable: - The server being reviewed is hosting SharePoint. - This IIS 10.0 installation is supporting Microsoft Exchange and not otherwise hosting any content.

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.

Double-click the "Request Filtering" icon.

Click "Edit Feature Settings" in the "Actions" pane.

If the "Allow high-bit characters" check box is checked, this is a finding.

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.