Ubuntu OS must generate audit records for successful/unsuccessful uses of the ssh-keysign command.

Without generating audit records that are specific to the security and mission needs of the organization, it would be difficult to establish, correlate, and investigate the events relating to an incident or identify those responsible for one.

Audit records can be generated from various components within the information system (e.g., module or policy filter).

Verify Ubuntu OS generates an audit record upon successful/unsuccessful attempts to use the "ssh-keysign" command by using the following command:

     $ sudo auditctl -l | grep ssh-keysign 
     -a always,exit -S all -F path=/usr/lib/openssh/ssh-keysign -F perm=x -F auid>=1000 -F auid!=-1 -F key=privileged-ssh  

If the command does not return lines that match the example or the lines are commented out, this is a finding.

Note: The "key=" value is arbitrary and can be different from the example output above.

Configure the audit system to generate an audit event for any successful/unsuccessful use of the "ssh-keysign" command.

Add or modify the following line in the "/etc/audit/rules.d/stig.rules" file:

-a always,exit -F path=/usr/lib/openssh/ssh-keysign -F perm=x -F auid>=1000 -F auid!=unset -k privileged-ssh

To reload the rules file, issue the following command:

     $ sudo augenrules --load 

Note: The "-k <keyname>" at the end of the line gives the rule a unique meaning to help during an audit investigation. The <keyname> does not need to match the example above.