AlmaLinux OS 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-269264	SRG-OS-000480-GPOS-00227	ALMA-09-020810	SV-269264r1050146_rule	2025-02-20	1

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: $ sshd -T \| grep hostbasedauthentication hostbasedauthentication no If the "HostbasedAuthentication" keyword is not set to "no", this is a finding.

✔️ Fix
Configure the AlmaLinux OS 9 SSH daemon to not allow a noncertificate trusted host SSH logon to the system with the following command: Add the following line to "/etc/ssh/sshd_config", or uncomment the line and set the value to "no": HostbasedAuthentication no Alternatively, add the setting to an include file if the line "Include /etc/ssh/sshd_config.d/*.conf" is found at the top of the "/etc/ssh/sshd_config" file: $ echo 'HostbasedAuthentication no' > /etc/ssh/sshd_config.d/40-hostbasedauthentication.conf Restart the SSH daemon for the settings to take effect: $ systemctl restart sshd.service

✔️ Fix

Configure the AlmaLinux OS 9 SSH daemon to not allow a noncertificate trusted host SSH logon to the system with the following command: Add the following line to "/etc/ssh/sshd_config", or uncomment the line and set the value to "no": HostbasedAuthentication no Alternatively, add the setting to an include file if the line "Include /etc/ssh/sshd_config.d/*.conf" is found at the top of the "/etc/ssh/sshd_config" file: $ echo 'HostbasedAuthentication no' > /etc/ssh/sshd_config.d/40-hostbasedauthentication.conf Restart the SSH daemon for the settings to take effect: $ systemctl restart sshd.service