The SUSE operating system must prevent Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) redirect messages from being accepted.
Severity | Group ID | Group Title | Version | Rule ID | Date | STIG Version |
|---|---|---|---|---|---|---|
| medium | V-235018 | SRG-OS-000480-GPOS-00227 | SLES-15-040330 | SV-235018r991589_rule | 2025-02-27 | 2 |
| 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. |
| ℹ️ Check |
|---|
| Verify the SUSE operating system does not accept IPv4 ICMP redirect messages. Check the value of the IPv4 accept_redirects variable with the following command: > sudo sysctl net.ipv4.conf.all.accept_redirects net.ipv4.conf.all.accept_redirects =0 If the network parameter "ipv4.conf.all.accept_redirects" is not equal to "0" or nothing is returned, this is a finding. |
| ✔️ Fix |
|---|
| Configure the SUSE operating system to not accept IPv4 ICMP redirect messages by running the following command as an administrator: > sudo sysctl -w net.ipv4.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.ipv4.conf.all.accept_redirects=0" >> /etc/sysctl.d/99-stig.conf' > sudo sysctl --system |