Title

The IIS 10.0 web server must not be both a website server and a proxy server. (Cat II impact)

Discussion

A web server should be primarily a web server or a proxy server but not both, for the same reasons that other multi-use servers are not recommended. Scanning for web servers that also proxy requests into an otherwise protected network is a common attack, making the attack anonymous.

Check Content

Open the IIS 10.0 Manager. Under the "Connections" pane on the left side of the management console, select the IIS 10.0 web server. If, under the IIS installed features "Application Request Routing Cache" is not present, this is not a finding. If, under the IIS installed features "Application Request Routing Cache" is present, double-click the icon to open the feature. From the right "Actions" pane under "Proxy", select "Server Proxy Settings...". In the "Application Request Routing" settings window, verify whether "Enable proxy" is selected. If "Enable proxy" is selected under the "Application Request Routing" settings, this is a finding. If the server has been approved to be a Proxy server, this requirement is Not Applicable.

Fix Text

Open the IIS 10.0 Manager. Under the "Connections" pane on the left side of the management console, select the IIS 10.0 web server. Under the IIS installed features, if "Application Request Routing Cache" is present, double-click the icon to open the feature. From the right "Actions" pane, under "Proxy", select "Server Proxy Settings...". In the "Application Request Routing" settings window, remove the check from the "Enable proxy" check box. Click "Apply" in the "Actions" pane.

Additional Identifiers

Rule ID: SV-218794r928918_rule

Vulnerability ID: V-218794

Group Title: SRG-APP-000141-WSR-000076

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.