If the underlying operating system of your portal installation is not sufficiently secured, attackers can exploit existing vulnerabilities at operating system level. For this reason the operating systems on all machines of your portal installation (Portal Server machine, persistence layer machine, and so on) should be hardened. Hardening the operating system means to configure it as securely as possible and includes the following:
· Apply all available patches to the operating system before using it for the portal.
· Deactivate or de-install any service that is not needed for the operation of the portal.