cis-apache24-5-9

name	cis-apache24-5.9
description	Ensure Old HTTP Protocol Versions Are Disallowed
category	cis-apache
version	2.3.0
author	cyberstrike-official
tags	["cis","apache","linux","features","content","options"]
cis_id	5.9
cis_benchmark	CIS Apache HTTP Server 2.4 Benchmark v2.3.0
tech_stack	["linux","apache"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

5.9 Ensure Old HTTP Protocol Versions Are Disallowed

Profile Applicability

• Level 1

Description

The Apache modules mod_rewrite or mod_security can be used to disallow old and invalid HTTP protocols versions. The HTTP version 1.1 RFC is dated June 1999 and has been supported by Apache since version 1.2. It should no longer be necessary to allow ancient versions of HTTP such as 1.0 and prior.

Rationale

Many malicious automated programs, vulnerability scanners and fingerprinting tools will send abnormal HTTP protocol versions to see how the web server responds. These requests are usually part of the attacker's enumeration process and therefore it is important that we respond by denying these requests.

Audit

Perform the following to determine if the recommended state is implemented:

1. Locate the Apache configuration files and included configuration files.
2. Verify there is a rewrite condition within the global server context that disallows requests that do not include the HTTP/1.1 as shown below.
3. RewriteEngine On
4. RewriteCond %{THE_REQUEST} !(HTTP/1\.1|HTTP/2\.0)$
5. RewriteRule .* - [F]
6. Verify the following directives are included in each section so that the main server settings will be inherited.
7. RewriteEngine On
8. RewriteOptions Inherit

Remediation

Perform the following to implement the recommended state:

1. Load the mod_rewrite module for Apache by doing either one of the following:
   • Build Apache with mod_rewrite statically loaded during the build, by adding the --enable-rewrite option to the ./configure script.
   • ./configure --enable-rewrite.
   • Or, dynamically loading the module with the LoadModule directive in the httpd.conf configuration file.
   • LoadModule rewrite_module modules/mod_rewrite.so
2. Set the apache2 profile to enforce mode, reload AppArmor, and then test the web site functionality again.
3. # aa-enforce /usr/sbin/apache2
4. # /etc/init.d/apparmor reload

Default Value

The default Apache profile is very permissive.

References