Non-ASCII characters in URLs must be prohibited by any IIS 10.0 website.
Severity | Group ID | Group Title | Version | Rule ID | Date | STIG Version |
|---|---|---|---|---|---|---|
| medium | V-218756 | SRG-APP-000246-WSR-000149 | IIST-SI-000228 | SV-218756r961152_rule | 2026-02-26 | 2 |
Description
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.
ℹ️ Check
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.
Note: If this IIS 10.0 installation is supporting Microsoft Exchange, and not otherwise hosting any content, this requirement is Not Applicable.
✔️ Fix
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.