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V-218824

CAT II (Medium)

Unspecified file extensions on a production IIS 10.0 web server must be removed.

Rule ID

SV-218824r961863_rule

STIG

Microsoft IIS 10.0 Server Security Technical Implementation Guide

Version

V3R7

CCIs

CCI-000366

Discussion

By allowing unspecified file extensions to execute, the web servers attack surface is significantly increased. This increased risk can be reduced by only allowing specific ISAPI extensions or CGI extensions to run on the web server.

Check Content

Open the IIS 10.0 Manager.

Click the IIS 10.0 web server name.

Double-click the "ISAPI and CGI restrictions" icon.

Click “Edit Feature Settings".

Verify the "Allow unspecified CGI modules" and the "Allow unspecified ISAPI modules" check boxes are NOT checked.

If either or both of the "Allow unspecified CGI modules" and the "Allow unspecified ISAPI modules" check boxes are checked, this is a finding.

Fix Text

Open the IIS 10.0 Manager.

Click the IIS 10.0 web server name.

Double-click the "ISAPI and CGI restrictions" icon.

Click "Edit Feature Settings".

Remove the check from the "Allow unspecified CGI modules" and the "Allow unspecified ISAPI modules" check boxes.

Click "OK".