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

STIG ID: SLES-12-030401 |  SRG: SRG-OS-000480-GPOS-00227 |  Severity: medium |  CCI:  | Vulnerability Id: V-217293

Vulnerability Discussion

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.

Check

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

Fix

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.