cis-apache-9-6

name	cis-apache-9.6
description	Ensure Timeout Limits for the Request Body Are Set Properly
category	cis-apache
version	3.6.0
author	cyberstrike-official
tags	["cis","apache","linux","dos","denial-of-service","timeout"]
cis_id	9.6
cis_benchmark	CIS Apache HTTP Server 2.2 Benchmark v3.6.0
tech_stack	["linux","apache"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

Ensure Timeout Limits for the Request Body Are Set Properly

Description

The RequestReadTimeout directive allows setting timeout values for the body portion of a request. The directive provides for an initial timeout value, a maximum timeout, and a minimum rate. The minimum rate specifies that after the initial timeout, the server will wait an additional second for each N bytes received. The recommended setting is to have a maximum timeout of 20 seconds or less.

Rationale

It is not sufficient to timeout only on the header portion of the request, as the server will still be vulnerable to attacks like the OWASP Slow POST attack, which provide the body of the request very slowly. Therefore, the body portion of the request must have a timeout as well. A timeout of 20 seconds or less is recommended.

Impact

None documented

Audit Procedure

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

1. Locate the Apache configuration files and included configuration files.
2. Locate any RequestReadTimeout directives and verify the configuration has a maximum body request timeout of 20 seconds or less.
3. If the configuration does not contain any RequestReadTimeout directives and the mod_reqtimeout module is being loaded, then the default value of 20 seconds is compliant with the benchmark recommendation.

RequestReadTimeout header=XXXXXX body=20,MinRate=XXXXXXXXXX

Remediation

Perform the following to implement the recommended state:

1. Load the mod_reqtimeout module in the Apache configuration with the following.

LoadModule reqtimeout_module modules/mod_reqtimeout.so

2. Add a RequestReadTimeout directive similar to the one below with the maximum request body timeout value of 20 seconds or less.

RequestReadTimeout header=20-40,MinRate=500 body=20,MinRate=500

Default Value

body=20,MinRate=500

References

1. https://httpd.apache.org/docs/2.2/mod/mod_reqtimeout.html

CIS Controls

Version 6

9 Limitation and Control of Network Ports, Protocols, and Services Limitation and Control of Network Ports, Protocols, and Services