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The SUSE operating system must not allow interfaces to accept Internet Protocol version 6 (IPv6) Internet Control Message Protocol (ICMP) redirect messages by default.


Overview

Finding ID Version Rule ID IA Controls Severity
V-217293 SLES-12-030401 SV-217293r603262_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-18521r370035_chk )
Verify the SUSE operating system does not allow IPv6 ICMP redirect messages by default.

Check the value of the "default accept_redirects" variables with the following command:

# sudo sysctl net.ipv6.conf.default.accept_redirects
net.ipv6.conf.default.accept_redirects = 0

If the returned line does not have a value of "0", this is a finding.
Fix Text (F-18519r370036_fix)
Configure the SUSE operating system to not allow IPv6 ICMP redirect messages by default.

Set the system to the required kernel parameter by adding the following line to "/etc/sysctl.conf" (or modify the line to have the required value):

net.ipv6.conf.default.accept_redirects=0

Run the following command to apply this value:

# sysctl –system