cis-ubuntu1204-v110-7-3-2

name	cis-ubuntu1204-v110-7-3-2
description	Disable IPv6 Redirect Acceptance
category	cis-os-hardening
version	1.1.0
author	cyberstrike-official
tags	["cis","ubuntu",12.04,"linux","networking","ipv6","redirects","sysctl"]
cis_id	7.3.2
cis_benchmark	CIS Ubuntu 12.04 LTS Server Benchmark v1.1.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

7.3.2 Disable IPv6 Redirect Acceptance (Not Scored)

Profile Applicability

• Level 1

Description

This setting prevents the system from accepting ICMP redirects. ICMP redirects tell the system about alternate routes for sending traffic.

Rationale

It is recommended that systems not accept ICMP redirects as they could be tricked into routing traffic to compromised machines. Setting hard routes within the system (usually a single default route to a trusted router) protects the system from bad routes.

Audit Procedure

Using Command Line

Perform the following to determine if IPv6 redirects are disabled.

/sbin/sysctl net.ipv6.conf.all.accept_redirects
/sbin/sysctl net.ipv6.conf.default.accept_redirects

Expected Result

net.ipv6.conf.all.accept_redirect = 0
net.ipv6.conf.default.accept_redirect = 0

Remediation

Using Command Line

Set the net.ipv6.conf.all.accept_redirects and net.ipv6.conf.default.accept_redirects parameters to 0 in /etc/sysctl.conf:

net.ipv6.conf.all.accept_redirects=0
net.ipv6.conf.default.accept_redirects=0

Modify active kernel parameters to match:

/sbin/sysctl -w net.ipv6.conf.all.accept_redirects=0
/sbin/sysctl -w net.ipv6.conf.default.accept_redirects=0
/sbin/sysctl -w net.ipv6.route.flush=1

Default Value

IPv6 redirect acceptance is enabled by default.

References

• CIS Ubuntu 12.04 LTS Server Benchmark v1.1.0

Profile

Level 1 - Not Scored