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The SUSE operating system must not allow interfaces to accept Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) redirect messages by default.


Overview

Finding ID Version Rule ID IA Controls Severity
V-217292 SLES-12-030400 SV-217292r603262_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 2022-12-06

Details

Check Text ( C-18520r370032_chk )
Verify the SUSE operating system ignores IPv4 ICMP redirect messages.

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

# sysctl net.ipv4.conf.default.accept_redirects
net.ipv4.conf.default.accept_redirects = 0

If the returned line does not have a value of "0" this is a finding.
Fix Text (F-18518r370033_fix)
Configure the SUSE operating system ignores IPv4 ICMP redirect messages by adding the following line to "/etc/sysctl.conf" (or modify the line to have the required value):

net.ipv4.conf.default.accept_redirects = 0

Run the following command to apply this value:

# sysctl --system