This will withstand brute force attacks by hackers to obtain the password.

• Use Yast to install ClamAV and it's offline database.
• Update database and run a complete scan.

    freshclam
    clamscan -r -i /
    

• Delete all infected files, if any.

• Copy the file authorzied_keys to /root/.ssh
• Edit the file sshd_config

    vi /etc/ssh/sshd_config
   
    

and add the following lines:

    PasswordAuthentication no
    ChallengeResponseAuthentication no

If root access is not permitted, check Login as root to fix the issue.