Automatic directory indexing must be disabled.

From APACHE 2.2 SERVER for Windows Security Technical Implementation Guide

SV-33225r1_rule Automatic directory indexing must be disabled.

Vulnerability discussion

To identify the type of web servers and versions software installed it is common for attackers to scan for icons or special content specific to the server type and version. A simple request like http://example.com/icons/apache_pb2.png may tell the attacker that the server is Apache 2.2 as shown below. The many icons are used primary for auto indexing, which is recommended to be disabled.

Check content

Open a command prompt window. Navigate to the “bin” directory (in many cases this may be [Drive Letter]:\[directory path]\Apache Software Foundation\Apache2.2\bin>). Enter the following command and press Enter: httpd –M This will provide a list of all loaded modules. If the following module is found this is a finding: autoindex_module.

Fix text

Disable the autoindex_module by adding a "#" in front of it within the httpd.conf file, and restarting the Apache httpd service.

Pro Tips

Lavender hyperlinks in small type off to the right (of CSS class id, if you view the page source) point to globally unique URIs for each document and item. Copy the link location and paste anywhere you need to talk unambiguously about these things.

You can obtain data about documents and items in other formats. Simply provide an HTTP header Accept: text/turtle or Accept: application/rdf+xml.