AIX7-00-001000 - AIX /etc/security/mkuser.sys.custom file must not exist unless it is needed for customizing a new user account.
The '/etc/security/mkuser.sys.custom' is called by '/etc/security/mkuser.sys' to customize the new user account when a new user is created, or a user is logging into the system without a home directory. An improper '/etc/security/mkuser.sys.custom' script increases the risk that non-privileged users may obtain elevated privileges. It must not exist unless it is needed.
Remove the '/etc/security/mkuser.sys.custom' file using the following command: # rm /etc/security/mkuser.sys.custom