cis-apache-4-1

name	cis-apache-4.1
description	Ensure Access to OS Root Directory Is Denied By Default
category	cis-apache
version	3.6.0
author	cyberstrike-official
tags	["cis","apache","linux","access-control","directory"]
cis_id	4.1
cis_benchmark	CIS Apache HTTP Server 2.2 Benchmark v3.6.0
tech_stack	["linux","apache"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

Ensure Access to OS Root Directory Is Denied By Default

Description

The Apache Directory directive allows for directory-specific configuration of access controls and many other features and options. One important usage is to create a default deny policy that does not allow access to OS directories and files, except for those specifically allowed. This is done by denying access to the OS root directory.

Rationale

One aspect of Apache that is occasionally misunderstood is the feature of default access. That is, unless you take steps to change it, if the server can find its way to a file through normal URL mapping rules, it can and will serve it to clients. Having a default deny helps prevent unintended access. The Order directive is important as it provides for other Allow directives to override the default deny.

Impact

None documented

Audit Procedure

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

1. Search the Apache configuration files (httpd.conf and any included configuration files) to find a root <Directory> element.
2. Ensure there is a single Order directive with the value of deny, allow.
3. Ensure there is a Deny directive and it has the value of from all.
4. Ensure there are no Allow or Require directives in the root <Directory> element.

The following may be useful in extracting root directory elements from the Apache configuration for auditing.

$ perl -ne 'print if /^ *<Directory *\*\/\//i .. /<\/Directory/i'
$APACHE_PREFIX/conf/httpd.conf

Remediation

Perform the following to implement the recommended state:

1. Search the Apache configuration files (httpd.conf and any included configuration files) to find a root <Directory> element.
2. Have a single Order directive and set its value to deny, allow.
3. Have a Deny directive and set its value to from all.
4. Remove all Allow directives from the root <Directory> element.

<Directory />
   . . .
   Order deny,allow
   Deny from all
   . . .
</Directory>