cyberstrikeus Ensure IP Address Based Requests Are Disallowed
Description
The Apache module mod_rewrite should disallow access for requests that use an IP address instead of a host name for the URL. Most normal access to the website from browsers and automated software will use a hostname, and will therefore include the hostname in the HTTP HOST header.
Refer to the Apache 2.2 documentation for details: http://httpd.apache.org/docs/2.2/mod/mod_rewrite.html
Rationale
A common malware propagation and automated network scanning technique is to use IP addresses rather than hostnames for web requests, since it's simpler to automate. By denying IP-based web requests, these automated techniques will be denied access to the website. Malicious web scanning techniques continue to evolve, and many are now using hostnames, but denying access to IP-based requests is still a worthwhile defensive measure.
Audit Procedure
Perform the following steps to determine if the recommended state is implemented:
- Locate the Apache configuration files and included configuration files.
- Verify there is a rewrite condition within the global server context that disallows IP-based requests by requiring a HTTP HOST header similar to the example shown below.
RewriteCond %{HTTP_HOST} !^www\.example\.com [NC]
RewriteCond %{REQUEST_URI} !^/error [NC]
RewriteRule ^.(.*) - [L,F]
Remediation
Perform the following to implement the recommended state:
Load the
mod_rewritemodule for Apache by doing either one of the following: a. Build Apache withmod_rewritestatically loaded during the build by adding the--enable-rewriteoption to the./configurescript./configure --enable-rewriteb. Or, dynamically load the module with the
LoadModuledirective in thehttpd.confconfiguration file.LoadModule rewrite_module modules/mod_rewrite.soAdd the
RewriteEnginedirective to the configuration within the global server context with the value ofonso the rewrite engine is enabled.
RewriteEngine On
- Locate the Apache configuration file such as
httpd.confand add the following rewrite condition to match the expected host name of the top server level configuration.
RewriteCond %{HTTP_HOST} !^www\.example\.com [NC]
RewriteCond %{REQUEST_URI} !^/error [NC]
RewriteRule ^.(.*) - [L,F]
Default Value
RewriteEngine off
References
CIS Controls
Version 6
9.1 Limit Open Ports, Protocols, and Services Ensure that only ports, protocols, and services with validated business needs are running on each system.
Version 7
9.2 Ensure Only Approved Ports, Protocols and Services Are Running Ensure that only network ports, protocols, and services listening on a system with validated business needs, are running on each system.
Profile
Level 2 | Scored