The SUSE operating system must prevent Internet Protocol version 6 (IPv6) Internet Control Message Protocol (ICMP) redirect messages from being accepted.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-237621	SLES-12-030363	SV-237621r646826_rule		Medium

Description
ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. These messages modify the host's route table and are unauthenticated. An illicit ICMP redirect message could result in a man-in-the-middle attack.

STIG	Date
SLES 12 Security Technical Implementation Guide	2022-09-13

Details

Check Text ( C-40840r646824_chk )

Verify the SUSE operating system does not accept IPv6 source-routed packets by default. Verify the SUSE operating system does not accept IPv6 ICMP redirect messages. Check the value of the IPv6 accept_redirects variable with the following command: > sudo sysctl net.ipv6.conf.all.accept_redirects net.ipv6.conf.all.accept_redirects =0 If the network parameter "ipv6.conf.all.accept_redirects" is not equal to "0" or nothing is returned, this is a finding.

Fix Text (F-40803r646825_fix)

Configure the SUSE operating system to not accept IPv6 ICMP redirect messages by running the following command as an administrator: > sudo sysctl -w net.ipv6.conf.all.accept_redirects=0 If "0" is not the system's default value, add or update the following line in "/etc/sysctl.d/99-stig.conf": > sudo sh -c 'echo "net.ipv6.conf.all.accept_redirects=0" >> /etc/sysctl.d/99-stig.conf' > sudo sysctl --system