RHEL 9 must not allow a noncertificate trusted host SSH logon to the system.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-257992	SRG-OS-000480-GPOS-00229	RHEL-09-255080	SV-257992r1045047_rule	2025-02-27	2

Description
SSH trust relationships mean a compromise on one host can allow an attacker to move trivially to other hosts.

ℹ️ Check
Verify the operating system does not allow a noncertificate trusted host SSH logon to the system with the following command: $ sudo /usr/sbin/sshd -dd 2>&1 \| awk '/filename/ {print $4}' \| tr -d '\r' \| tr '\n' ' ' \| xargs sudo grep -iH '^\s*hostbasedauthentication' HostbasedAuthentication no If the "HostbasedAuthentication" keyword is not set to "no", is missing, or is commented out, this is a finding. If the required value is not set, this is a finding.

ℹ️ Check

Verify the operating system does not allow a noncertificate trusted host SSH logon to the system with the following command: $ sudo /usr/sbin/sshd -dd 2>&1 | awk '/filename/ {print $4}' | tr -d '\r' | tr '\n' ' ' | xargs sudo grep -iH '^\s*hostbasedauthentication' HostbasedAuthentication no If the "HostbasedAuthentication" keyword is not set to "no", is missing, or is commented out, this is a finding. If the required value is not set, this is a finding.

✔️ Fix
To configure RHEL 9 to not allow a noncertificate trusted host SSH logon to the system, add or modify the following line in "/etc/ssh/sshd_config" or in a file in "/etc/ssh/sshd_config.d". HostbasedAuthentication no Restart the SSH daemon for the settings to take effect: $ sudo systemctl restart sshd.service