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V-269264

CAT II (Medium)

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

Rule ID

SV-269264r1050146_rule

STIG

Cloud Linux AlmaLinux OS 9 Security Technical Implementation Guide

Version

V1R6

CCIs

CCI-000366

Discussion

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

Check Content

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 Text

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